Search Results

Search found 5267 results on 211 pages for 'use cases'.

Page 198/211 | < Previous Page | 194 195 196 197 198 199 200 201 202 203 204 205  | Next Page >

• Debugging EXC_BAD_ACCESS that occurs only on release target for an iPhone app?

  - by Bobby Moretti

  I'm developing an iPhone application. I have an EXC_BAD_ACCESS that occurs only in the release target; when I build the debug target the exception does not occur. However, when I set the NSZombieEnabled environment variable to YES, I still get the EXC_BAD_ACCESS with no further information. Is it even possible for NSZombieEnabled to work when executing the release target? I don't see why not, since gdb is running in both cases... Update: here is a printout of the top of the stack: #0 0x33369ebc in objc_msgSend () #1 0x3144f968 in -[EAInputStream _streamEventTrigger] () #2 0x3144fe78 in __streamEventTrigger () #3 0x338ae3a6 in CFRunLoopRunSpecific () #4 0x338adc1e in CFRunLoopRunInMode () #5 0x32ed6966 in -[NSRunLoop(NSRunLoop) runMode:beforeDate:] () #6 0x00005b06 in -[IOStreamDelegate removeMsg:] (self=0x142cc0, _cmd=<value temporarily unavailable, due to optimizations>, message=0x2fffe544) at /Users/robertmoretti/Documents/XXXXXXX/IOStreamDelegate.m:191 Here is a gdb session from inside the objc_msgSend call at the top: (gdb) p/x $r0 $6 = 0x3100000 (gdb) x/s $r1 0x32d7cff8: "release" (gdb) disassemble $pc Dump of assembler code for function objc_msgSend: 0x33369ea8 <objc_msgSend+0>: teq r0, #0 ; 0x0 0x33369eac <objc_msgSend+4>: moveq r1, #0 ; 0x0 0x33369eb0 <objc_msgSend+8>: bxeq lr 0x33369eb4 <objc_msgSend+12>: push {r3, r4, r5, r6} 0x33369eb8 <objc_msgSend+16>: ldr r4, [r0] 0x33369ebc <objc_msgSend+20>: ldr r5, [r4, #8] 0x33369ec0 <objc_msgSend+24>: ldr r6, [r5] 0x33369ec4 <objc_msgSend+28>: add r3, r5, #8 ; 0x8 0x33369ec8 <objc_msgSend+32>: and r5, r6, r1, lsr #2 0x33369ecc <objc_msgSend+36>: ldr r4, [r3, r5, lsl #2] 0x33369ed0 <objc_msgSend+40>: teq r4, #0 ; 0x0 0x33369ed4 <objc_msgSend+44>: add r5, r5, #1 ; 0x1 0x33369ed8 <objc_msgSend+48>: beq 0x33369efc <objc_msgSend+84> 0x33369edc <objc_msgSend+52>: ldr r12, [r4] 0x33369ee0 <objc_msgSend+56>: teq r1, r12 0x33369ee4 <objc_msgSend+60>: and r5, r5, r6 0x33369ee8 <objc_msgSend+64>: bne 0x33369ecc <objc_msgSend+36> 0x33369eec <objc_msgSend+68>: ldr r12, [r4, #8] 0x33369ef0 <objc_msgSend+72>: teq r4, r4 0x33369ef4 <objc_msgSend+76>: pop {r3, r4, r5, r6} 0x33369ef8 <objc_msgSend+80>: bx r12 0x33369efc <objc_msgSend+84>: pop {r3, r4, r5, r6} 0x33369f00 <objc_msgSend+88>: b 0x33369f04 <objc_msgSend_uncached> End of assembler dump. (gdb) p/x *$r0 $9 = 0x0 The exception occurs on the line 0x33369ebc <objc_msgSend+20>: ldr r5, [r4, #8]. r4 has just been given the value pointed to by r0, which happens to be 0. I am wondering what is supposed to be in the memory region of 0x3100000. Here's a memory dump of that area: (gdb) x/256w 0x3100000 0x3100000: 0x00000000 0x0000a293 0xaa650505 0x00000000 0x3100010: 0x0000a294 0xaa670505 0x00000000 0x0000a295 0x3100020: 0xaa690505 0x00000000 0x0000a296 0xaa6b0505 0x3100030: 0x00000000 0x0000a297 0xaa6d0505 0x00000000 0x3100040: 0x0000a298 0xaa6f0505 0x00000000 0x0000a299 0x3100050: 0xaa710505 0x00000000 0x0000a29a 0xaa730505 0x3100060: 0x00000000 0x0000a29b 0xaa750505 0x00000000 0x3100070: 0x0000a29c 0xaa770505 0x00000000 0x0000a29d 0x3100080: 0xaa790505 0x00000000 0x0000a29e 0xaa7b0505 0x3100090: 0x00000000 0x0000a29f 0xaa7d0505 0x00000000 0x31000a0: 0x0000a2a0 0xaa7f0505 0x00000000 0x0000a2a1 0x31000b0: 0xaa810505 0x00000000 0x0000a2a2 0xaa830505 0x31000c0: 0x00000000 0x0000a2a3 0xaa850505 0x00000000 0x31000d0: 0x0000a2a4 0xaa870505 0x00000000 0x0000a2a5 0x31000e0: 0xaa890505 0x00000000 0x0000a2a6 0xaa8b0505 0x31000f0: 0x00000000 0x0000a2a7 0xaa8d0505 0x00000000 0x3100100: 0x0000a2a8 0xaa8f0505 0x00000000 0x0000a2a9 0x3100110: 0xaa910505 0x00000000 0x0000a2aa 0xaa930505 0x3100120: 0x00000000 0x0000a2ab 0xaa950505 0x00000000 0x3100130: 0x0000a2ac 0xaa970505 0x00000000 0x0000a2ad 0x3100140: 0xaa990505 0x00000000 0x0000a2ae 0xaa9b0505 0x3100150: 0x00000000 0x0000a2af 0xaa9d0505 0x00000000 0x3100160: 0x0000a2b0 0xaa9f0505 0x00000000 0x0000a2b1 0x3100170: 0xaaa10505 0x00000000 0x0000a2b2 0xaaa30505 0x3100180: 0x00000000 0x0000a2b3 0xaaa50505 0x00000000 0x3100190: 0x0000a2b4 0xaaa70505 0x00000000 0x0000a2b5 0x31001a0: 0xaaa90505 0x00000000 0x0000a2b6 0xaaab0505 0x31001b0: 0x00000000 0x0000a2b7 0xaaad0505 0x00000000 0x31001c0: 0x0000a2b8 0xaaaf0505 0x00000000 0x0000a2b9 0x31001d0: 0xaab10505 0x00000000 0x0000a2ba 0xaab30505 0x31001e0: 0x00000000 0x0000a2bb 0xaab50505 0x00000000 0x31001f0: 0x0000a2bc 0xaab70505 0x00000000 0x0000a2bd 0x3100200: 0xaab90505 0x00000000 0x0000a2be 0xaabb0505 0x3100210: 0x00000000 0x0000a2bf 0xaabd0505 0x00000000 0x3100220: 0x0000a2c0 0xaabf0505 0x00000000 0x0000a2c1 0x3100230: 0xaac10505 0x00000000 0x0000a2c2 0xaac30505 0x3100240: 0x00000000 0x0000a2c3 0xaac50505 0x00000000 0x3100250: 0x0000a2c4 0xaac70505 0x00000000 0x0000a2c5 0x3100260: 0xaac90505 0x00000000 0x0000a2c6 0xaacb0505 0x3100270: 0x00000000 0x0000a2c7 0xaacd0505 0x00000000 0x3100280: 0x0000a2c8 0xaacf0505 0x00000000 0x0000a2c9 0x3100290: 0xaad10505 0x00000000 0x0000a2ca 0xaad30505 0x31002a0: 0x00000000 0x0000a2cb 0xaad50505 0x00000000 0x31002b0: 0x0000a2cc 0xaad70505 0x00000000 0x0000a2cd 0x31002c0: 0xaad90505 0x00000000 0x0000a2ce 0xaadb0505 0x31002d0: 0x00000000 0x0000a2cf 0xaadd0505 0x00000000 0x31002e0: 0x0000a2d0 0xaadf0505 0x00000000 0x0000a2d1 0x31002f0: 0xaae10505 0x00000000 0x0000a2d2 0xaae30505 0x3100300: 0x00000000 0x0000a2d3 0xaae50505 0x00000000 0x3100310: 0x0000a2d4 0xaae70505 0x00000000 0x0000a2d5 0x3100320: 0xaae90505 0x00000000 0x0000a2d6 0xaaeb0505 0x3100330: 0x00000000 0x0000a2d7 0xaaed0505 0x00000000 0x3100340: 0x0000a2d8 0xaaef0505 0x00000000 0x0000a2d9 0x3100350: 0xaaf10505 0x00000000 0x0000a2da 0xaaf30505 0x3100360: 0x00000000 0x0000a2db 0xaaf50505 0x00000000 0x3100370: 0x0000a2dc 0xaaf70505 0x00000000 0x0000a2dd 0x3100380: 0xaaf90505 0x00000000 0x0000a2de 0xaafb0505 0x3100390: 0x00000000 0x0000a2df 0xaafd0505 0x00000000 0x31003a0: 0x0000a2e0 0xab050505 0x00000000 0x0000a2e1 0x31003b0: 0xab070505 0x00000000 0x0000a2e2 0xab090505 0x31003c0: 0x00000000 0x0000a2e3 0xab0b0505 0x00000000 0x31003d0: 0x0000a2e4 0xab0d0505 0x00000000 0x0000a2e5 0x31003e0: 0xab0f0505 0x00000000 0x0000a2e6 0xab110505 0x31003f0: 0x00000000 0x0000a2e7 0xab130505 0x00000000 I don't really know what else to try; hopefully someone with more iphone experience will be able to recognize this memory as something meaningful.

  Read the article

• Detecting Acceleration in a car (iPhone Accelerometer)

  - by TheGazzardian

  Hello, I am working on an iPhone app where we are trying to calculate the acceleration of a moving car. Similar apps have accomplished this (Dynolicious), but the difference is that this app is designed to be used during general city driving, not on a drag strip. This leads us to one big concern that Dynolicious was luckily able to avoid: hills. Yes, hills. There are two important stages to this: calibration, and actual driving. Our initial run was simple and suffered the consequences. During the calibration stage, I took the average force on the phone, and during running, I just subtracted the average force from the current force to get the current acceleration this frame. The problem with this is that the typical car receives much more force than just the forward force - everything from turning to potholes was causing the values to go out of sync with what was really happening. The next run was to add the condition that the iPhone must be oriented in such a way that the screen was facing toward the back of the car. Using this method, I attempted to follow only force on the z-axis, but this obviously lead to problems unless the iPhone was oriented directly upright, because of gravity. Some trigonometry later, and I had managed to work gravity out of the equation, so that the car was actually being read very, very well by the iPhone. Until I hit a slope. As soon as the angle of the car changed, suddenly I was receiving accelerations and decelerations that didn't make sense, and we were once again going out of sync. Talking with someone a lot smarter than me at math lead to a solution that I have been trying to implement for longer than I would like to admit. It's steps are as follows: 1) During calibration, measure gravity as a vector instead of a size. Store that vector. 2) When the car initially moves forward, take the vector of motion and subtract gravity. Use this as the forward momentum. (Ignore, for now, the user cases where this will be difficult and let's concentrate on the math :) 3) From the forward vector and the gravity vector, construct a plane. 4) Whenever a force is received, project it onto said plane to get rid of sideways force/etc. 5) Then, use that force, the known magnitude of gravity, and the known direction of forward motion to essentially solve a triangle to get the forward vector. The problem that is causing the most difficulty in this new system is not step 5, which I have gotten to the point where all the numbers look as they should. The difficult part is actually the detection of the forward vector. I am selecting vectors whose magnitude exceeds gravity, and from there, averaging them and subtracting gravity. (I am doing some error checking to make sure that I am not using a force just because the iPhone accelerometer was off by a bit, which happens more frequently than I would like). But if I plot these vectors that I am using, they actually vary by an angle of about 20-30 degrees, which can lead to some strong inaccuracies. The end result is that the app is even more inaccurate now than before. So basically - all you math and iPhone brains out there - any glaring errors? Any potentially better solutions? Any experience that could be useful at all? Award: offering a bounty of $250 to the first answer that leads to a solution.

  Read the article

• Decentralized synchronized secure data storage

  - by Alberich

  Introduction Hi, I am going to ask a question which seems utopic for me, but I need to know if there is a way to achieve what I need. And if not, I need to know why not. The idea Suppose I have a database structure, in MySql. I want to create some solution to allow anyone (no matter who, no matter where) to have a synchronized copy (updated clone) of this database (with its content) Well, and it is not going to be just one synchronized copy, it could (and should) be a multiple replication (supposing the basic, this means, for example, ten copies all over the world) And, the most important thing: It must be secure. By secure I mean only real-accepted transactions will be synchronized with all the others (no matter how many) database copies/clones. Note: Since it would be quite difficult to make the synchronization in real-time, I will design everything to make this feature dispensable. So it is not required. My auto-suggestion This is how I am thinking to manage it: Time identifiers and Updates checking: Every action (insert, update, delete...) will be stored as the action instruction itself, associated to the time identifier. [I think better than a DATETIME field, it'll be an INT one, with the number of miliseconds passed from 1st january 2013 on, for example]. So each copy is going to ask to the "neighbour copy" for new actions done since last update, and execute them after checking they are allowed. Problem 1: the "neighbour copy" could be outdated too. Solution 1: do not ask just one neighbour, create a random list with some of the copies/clones and ask them for news (I could avoid the list and ask ALL the clones for updates, but this will be inefficient if clones number ascends too much). Problem 2: Real-time global synchronization is not active. What if... Someone at CLONE_ENTERPRISING inserts a row into TABLE. ... this row goes to every clone ... Someone at CLONE_FIXEMALL deletes this row. ... and at the same time, somewhere in an outdated clone ... Someone at CLONE_DROPOUT edits this row (now inexistent at the other clones) Solution 2: easy stuff, force a GLOBAL synchronization before doing any new "depending-on-third-data action" (edit, for example). This global synch. will be unnecessary when making an INSERT, for instance. Note: Well, someone could have some fun, and make the same insert in two clones... since they're not getting updated in real-time, this row will exist twice. But, it's the same as when we have one single database, in some needed cases we check if there is an existing same-row before doing the final action. Not a problem. Problem 3: It is possible to edit the code and do not filter actions, so someone could spread instructions to delete everything, or just make some trolling activity. This is not a problem, since good clones will always be somewhere. Those who got bad won't interest anymore. I really appreciate if you read. I know this is not the perfect solution, it has possibly hundred of holes, but it is my basic start. I will now appreciate anything you can teach me now. Thanks a lot. PS.: It could be that all this I am trying already exists and has its own name. Sorry for asking then (I'd anyway thank this name, if it exists)

  Read the article

• How do I return a message if $_GET is null or does not match any database entries?

  - by CT

  I am working on designing an IT Asset database. Here I am working on a page used to view details on a specific asset determined by an asset id. Here I grab $id from $_GET["id"]; When $id is null, the page does not load. When $id does not match any entry within the database, the page loads but no asset table is printed. In both these cases, I would like to display a message like "There is no database entry for that Asset ID" How would this be handled? Thank you. <?php /* * View Asset * */ # include functions script include "functions.php"; $id = $_GET["id"]; ConnectDB(); $type = GetAssetType($id); ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="stylesheet" type="text/css" href="style.css" /> <title>Wagman IT Asset</title> </head> <body> <div id="page"> <div id="header"> <img src="images/logo.png" /> </div> </div> <div id="content"> <div id="container"> <div id="main"> <div id="menu"> <ul> <table width="100%" border="0"> <tr> <td width="15%"></td> <td width="30%%"><li><a href="index.php">Search Assets</a></li></td> <td width="30%"><li><a href="addAsset.php">Add Asset</a></li></td> <td width="25%"></td> </tr> </table> </ul> </div> <div id="text"> <ul> <li> <h1>View Asset</h1> </li> </ul> <br /> <?php switch ($type){ case "Server": $result = QueryServer($id); $ServerArray = GetServerData($result); PrintServerTable($ServerArray); break; case "Desktop"; break; case "Laptop"; break; } ?> </div> </div> </div> <div class="clear"></div> <div id="footer" align="center"> <p>&nbsp;</p> </div> </div> <div id="tagline"> Wagman Construction - Bridging Generations since 1902 </div> </body> </html>

  Read the article

• Why might a System.String object not cache its hash code?

  - by Dan Tao

  A glance at the source code for string.GetHashCode using Reflector reveals the following (for mscorlib.dll version 4.0): public override unsafe int GetHashCode() { fixed (char* str = ((char*) this)) { char* chPtr = str; int num = 0x15051505; int num2 = num; int* numPtr = (int*) chPtr; for (int i = this.Length; i > 0; i -= 4) { num = (((num << 5) + num) + (num >> 0x1b)) ^ numPtr[0]; if (i <= 2) { break; } num2 = (((num2 << 5) + num2) + (num2 >> 0x1b)) ^ numPtr[1]; numPtr += 2; } return (num + (num2 * 0x5d588b65)); } } Now, I realize that the implementation of GetHashCode is not specified and is implementation-dependent, so the question "is GetHashCode implemented in the form of X or Y?" is not really answerable. I'm just curious about a few things: If Reflector has disassembled the DLL correctly and this is the implementation of GetHashCode (in my environment), am I correct in interpreting this code to indicate that a string object, based on this particular implementation, would not cache its hash code? Assuming the answer is yes, why would this be? It seems to me that the memory cost would be minimal (one more 32-bit integer, a drop in the pond compared to the size of the string itself) whereas the savings would be significant, especially in cases where, e.g., strings are used as keys in a hashtable-based collection like a Dictionary<string, [...]>. And since the string class is immutable, it isn't like the value returned by GetHashCode will ever even change. What could I be missing? UPDATE: In response to Andras Zoltan's closing remark: There's also the point made in Tim's answer(+1 there). If he's right, and I think he is, then there's no guarantee that a string is actually immutable after construction, therefore to cache the result would be wrong. Whoa, whoa there! This is an interesting point to make (and yes it's very true), but I really doubt that this was taken into consideration in the implementation of GetHashCode. The statement "therefore to cache the result would be wrong" implies to me that the framework's attitude regarding strings is "Well, they're supposed to be immutable, but really if developers want to get sneaky they're mutable so we'll treat them as such." This is definitely not how the framework views strings. It fully relies on their immutability in so many ways (interning of string literals, assignment of all zero-length strings to string.Empty, etc.) that, basically, if you mutate a string, you're writing code whose behavior is entirely undefined and unpredictable. I guess my point is that for the author(s) of this implementation to worry, "What if this string instance is modified between calls, even though the class as it is publicly exposed is immutable?" would be like for someone planning a casual outdoor BBQ to think to him-/herself, "What if someone brings an atomic bomb to the party?" Look, if someone brings an atom bomb, party's over.

  Read the article

• Problem when trying to use simple Shaders + VBOs

  - by Mr.Gando

  Hello I'm trying to convert the following functions to a VBO based function for learning purposes, it displays a static texture on screen. I'm using OpenGL ES 2.0 with shaders on the iPhone (should be almost the same than regular OpenGL in this case), this is what I got working: //Works! - (void) drawAtPoint:(CGPoint)point depth:(CGFloat)depth { GLfloat coordinates[] = { 0, 1, 1, 1, 0, 0, 1, 0 }; GLfloat width = (GLfloat)_width * _maxS, height = (GLfloat)_height * _maxT; GLfloat vertices[] = { -width / 2 + point.x, -height / 2 + point.y, width / 2 + point.x, -height / 2 + point.y, -width / 2 + point.x, height / 2 + point.y, width / 2 + point.x, height / 2 + point.y, }; glBindTexture(GL_TEXTURE_2D, _name); //Attrib position and attrib_tex coord are handles for the shader attributes glVertexAttribPointer(ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices); glEnableVertexAttribArray(ATTRIB_POSITION); glVertexAttribPointer(ATTRIB_TEXCOORD, 2, GL_FLOAT, GL_FALSE, 0, coordinates); glEnableVertexAttribArray(ATTRIB_TEXCOORD); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); } I tried to do this to convert to a VBO however I don't see anything displaying on-screen with this version: //Doesn't display anything - (void) drawAtPoint:(CGPoint)point depth:(CGFloat)depth { GLfloat width = (GLfloat)_width * _maxS, height = (GLfloat)_height * _maxT; GLfloat position[] = { -width / 2 + point.x, -height / 2 + point.y, width / 2 + point.x, -height / 2 + point.y, -width / 2 + point.x, height / 2 + point.y, width / 2 + point.x, height / 2 + point.y, }; //Texture on-screen position ( each vertex is x,y in on-screen coords ) GLfloat coordinates[] = { 0, 1, 1, 1, 0, 0, 1, 0 }; // Texture coords from 0 to 1 glBindVertexArrayOES(vao); glGenVertexArraysOES(1, &vao); glGenBuffers(2, vbo); //Buffer 1 glBindBuffer(GL_ARRAY_BUFFER, vbo[0]); glBufferData(GL_ARRAY_BUFFER, 8 * sizeof(GLfloat), position, GL_STATIC_DRAW); glEnableVertexAttribArray(ATTRIB_POSITION); glVertexAttribPointer(ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, position); //Buffer 2 glBindBuffer(GL_ARRAY_BUFFER, vbo[1]); glBufferData(GL_ARRAY_BUFFER, 8 * sizeof(GLfloat), coordinates, GL_DYNAMIC_DRAW); glEnableVertexAttribArray(ATTRIB_TEXCOORD); glVertexAttribPointer(ATTRIB_TEXCOORD, 2, GL_FLOAT, GL_FALSE, 0, coordinates); //Draw glBindVertexArrayOES(vao); glBindTexture(GL_TEXTURE_2D, _name); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); } In both cases I'm using this simple Vertex Shader //Vertex Shader attribute vec2 position;//Bound to ATTRIB_POSITION attribute vec4 color; attribute vec2 texcoord;//Bound to ATTRIB_TEXCOORD varying vec2 texcoordVarying; uniform mat4 mvp; void main() { //You CAN'T use transpose before in glUniformMatrix4fv so... here it goes. gl_Position = mvp * vec4(position.x, position.y, 0.0, 1.0); texcoordVarying = texcoord; } The gl_Position is equal to product of mvp * vec4 because I'm simulating glOrthof in 2D with that mvp And this Fragment Shader //Fragment Shader uniform sampler2D sampler; varying mediump vec2 texcoordVarying; void main() { gl_FragColor = texture2D(sampler, texcoordVarying); } I really need help with this, maybe my shaders are wrong for the second case ? thanks in advance.

  Read the article

• Languages and VMs: Features that are hard to optimize and why

  - by mrjoltcola

  I'm doing a survey of features in preparation for a research project. Name a mainstream language or language feature that is hard to optimize, and why the feature is or isn't worth the price paid, or instead, just debunk my theories below with anecdotal evidence. Before anyone flags this as subjective, I am asking for specific examples of languages or features, and ideas for optimization of these features, or important features that I haven't considered. Also, any references to implementations that prove my theories right or wrong. Top on my list of hard to optimize features and my theories (some of my theories are untested and are based on thought experiments): 1) Runtime method overloading (aka multi-method dispatch or signature based dispatch). Is it hard to optimize when combined with features that allow runtime recompilation or method addition. Or is it just hard, anyway? Call site caching is a common optimization for many runtime systems, but multi-methods add additional complexity as well as making it less practical to inline methods. 2) Type morphing / variants (aka value based typing as opposed to variable based) Traditional optimizations simply cannot be applied when you don't know if the type of someting can change in a basic block. Combined with multi-methods, inlining must be done carefully if at all, and probably only for a given threshold of size of the callee. ie. it is easy to consider inlining simple property fetches (getters / setters) but inlining complex methods may result in code bloat. The other issue is I cannot just assign a variant to a register and JIT it to the native instructions because I have to carry around the type info, or every variable needs 2 registers instead of 1. On IA-32 this is inconvenient, even if improved with x64's extra registers. This is probably my favorite feature of dynamic languages, as it simplifies so many things from the programmer's perspective. 3) First class continuations - There are multiple ways to implement them, and I have done so in both of the most common approaches, one being stack copying and the other as implementing the runtime to use continuation passing style, cactus stacks, copy-on-write stack frames, and garbage collection. First class continuations have resource management issues, ie. we must save everything, in case the continuation is resumed, and I'm not aware if any languages support leaving a continuation with "intent" (ie. "I am not coming back here, so you may discard this copy of the world"). Having programmed in the threading model and the contination model, I know both can accomplish the same thing, but continuations' elegance imposes considerable complexity on the runtime and also may affect cache efficienty (locality of stack changes more with use of continuations and co-routines). The other issue is they just don't map to hardware. Optimizing continuations is optimizing for the less-common case, and as we know, the common case should be fast, and the less-common cases should be correct. 4) Pointer arithmetic and ability to mask pointers (storing in integers, etc.) Had to throw this in, but I could actually live without this quite easily. My feelings are that many of the high-level features, particularly in dynamic languages just don't map to hardware. Microprocessor implementations have billions of dollars of research behind the optimizations on the chip, yet the choice of language feature(s) may marginalize many of these features (features like caching, aliasing top of stack to register, instruction parallelism, return address buffers, loop buffers and branch prediction). Macro-applications of micro-features don't necessarily pan out like some developers like to think, and implementing many languages in a VM ends up mapping native ops into function calls (ie. the more dynamic a language is the more we must lookup/cache at runtime, nothing can be assumed, so our instruction mix is made up of a higher percentage of non-local branching than traditional, statically compiled code) and the only thing we can really JIT well is expression evaluation of non-dynamic types and operations on constant or immediate types. It is my gut feeling that bytecode virtual machines and JIT cores are perhaps not always justified for certain languages because of this. I welcome your answers.

  Read the article

• How to stop OpenGL from applying blending to certain content? (see pics)

  - by RexOnRoids

  Supporting Info: I use cocos2d to draw a sprite (graph background) on the screen (z:-1). I then use cocos2d to draw lines/points (z:0) on top of the background -- and make some calls to OpenGL blending functions before the drawing to SMOOTH out the lines. Problem: The problem is that: aside from producing smooth lines/points, calling these OpenGL blending functions seems to "degrade" the underlying sprite (graph background). As you can see from the images below, the "degraded" background seems to be made darker and less sharp in Case 2. So there is a tradeoff: I can either have (Case 1) a nice background and choppy lines/points, or I can have (Case 2) nice smooth lines/points and a degraded background. But obviously I need both. THE QUESTION: How do I set OpenGL so as to only apply the blending to the layer with the Lines/Points in it and thus leave the background alone? The Code: I have included code of the draw() method of the CCLayer for both cases explained above. As you can see, the code producing the difference between Case 1 and Case 2 seems to be 1 or 2 lines involving OpenGL Blending. Case 1 -- MainScene.h (CCLayer): -(void)draw{ int lastPointX = 0; int lastPointY = 0; GLfloat colorMAX = 255.0f; GLfloat valR; GLfloat valG; GLfloat valB; if([self.myGraphManager ready]){ valR = (255.0f/colorMAX)*1.0f; valG = (255.0f/colorMAX)*1.0f; valB = (255.0f/colorMAX)*1.0f; NSEnumerator *enumerator = [[self.myGraphManager.currentCanvas graphPoints] objectEnumerator]; GraphPoint* object; while ((object = [enumerator nextObject])) { if(object.filled){ /*Commenting out the following two lines induces a problem of making it impossible to have smooth lines/points, but has merit in that it does not degrade the background sprite.*/ //glEnable (GL_BLEND); //glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glHint (GL_LINE_SMOOTH_HINT, GL_DONT_CARE); glEnable (GL_LINE_SMOOTH); glLineWidth(1.5f); glColor4f(valR, valG, valB, 1.0); ccDrawLine(ccp(lastPointX, lastPointY), ccp(object.position.x, object.position.y)); lastPointX = object.position.x; lastPointY = object.position.y; glPointSize(3.0f); glEnable(GL_POINT_SMOOTH); glHint(GL_POINT_SMOOTH_HINT, GL_NICEST); ccDrawPoint(ccp(lastPointX, lastPointY)); } } } } Case 2 -- MainScene.h (CCLayer): -(void)draw{ int lastPointX = 0; int lastPointY = 0; GLfloat colorMAX = 255.0f; GLfloat valR; GLfloat valG; GLfloat valB; if([self.myGraphManager ready]){ valR = (255.0f/colorMAX)*1.0f; valG = (255.0f/colorMAX)*1.0f; valB = (255.0f/colorMAX)*1.0f; NSEnumerator *enumerator = [[self.myGraphManager.currentCanvas graphPoints] objectEnumerator]; GraphPoint* object; while ((object = [enumerator nextObject])) { if(object.filled){ /*Enabling the following two lines gives nice smooth lines/points, but has a problem in that it degrades the background sprite.*/ glEnable (GL_BLEND); glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glHint (GL_LINE_SMOOTH_HINT, GL_DONT_CARE); glEnable (GL_LINE_SMOOTH); glLineWidth(1.5f); glColor4f(valR, valG, valB, 1.0); ccDrawLine(ccp(lastPointX, lastPointY), ccp(object.position.x, object.position.y)); lastPointX = object.position.x; lastPointY = object.position.y; glPointSize(3.0f); glEnable(GL_POINT_SMOOTH); glHint(GL_POINT_SMOOTH_HINT, GL_NICEST); ccDrawPoint(ccp(lastPointX, lastPointY)); } } } }

  Read the article

• Losing data after reading them correct from file

  - by user1388172

  i have the fallowing class of object with a class a data structure which i use in main combined. The ADT(abstract data type) is a linked list. After i read from file the input data and create and object which at print looks just fine after a print. after i push_back() the 3-rd int variable get initializated to 0. So example and code: Example: ex.in: 1 7 31 2 2 2 3 3 3 now i create objects from each line, which at print look as they suppose, but after push_back(): 1 7 0 2 2 0 3 3 0 Class.h: class RAngle { private: int x,y,l,b; public: int solution,prec; RAngle(){ x = y = solution = prec = b = l =0; } RAngle(int i,int j,int k){ x = i; y = j; l = k; solution = 0; prec=0; b=0; } friend ostream& operator << (ostream& out, const RAngle& ra){ out << ra.x << " " << ra.y << " " << ra.l <<endl; return out; } friend istream& operator >>( istream& is, RAngle& ra){ is >> ra.x; is >> ra.y; is >> ra.l; return is ; } }; ADT.h: template <class T> class List { private: struct Elem { T data; Elem* next; }; Elem* first; T pop_front(){ if (first!=NULL) { T aux = first->data; first = first->next; return aux; } T a; return a; } void push_back(T data){ Elem *n = new Elem; n->data = data; n->next = NULL; if (first == NULL) { first = n; return ; } Elem *current; for(current=first;current->next != NULL;current=current->next); current->next = n; } Main.cpp(after i call this function in main which prints object as they suppose to be the x var(from RAngle class) changes to 0 in all cases.) void readData(List <RAngle> &l){ RAngle r; ifstream f_in; f_in.open("ex.in",ios::in); for(int i=0;i<10;++i){ f_in >> r; cout << r; l.push_back(r); }

  Read the article

• Doxygen for C++ template class member specialization

  - by Ziv

  When I write class templates, and need to fully-specialize members of those classes, Doxygen doesn't recognize the specialization - it documents only the generic definition, or (if there are only specializations) the last definition. Here's a simple example: ===MyClass.hpp=== #ifndef MYCLASS_HPP #define MYCLASS_HPP template<class T> class MyClass{ public: static void foo(); static const int INT_CONST; static const T TTYPE_CONST; }; /* generic definitions */ template<class T> void MyClass<T>::foo(){ printf("Generic foo\n"); } template<class T> const int MyClass<T>::INT_CONST = 5; /* specialization declarations */ template<> void MyClass<double>::foo(); template<> const int MyClass<double>::INT_CONST; template<> const double MyClass<double>::TTYPE_CONST; template<> const char MyClass<char>::TTYPE_CONST; #endif === MyClass.cpp === #include "MyClass.hpp" /* specialization definitions */ template<> void MyClass<double>::foo(){ printf("Specialized double foo\n"); } template<> const int MyClass<double>::INT_CONST = 10; template<> const double MyClass<double>::TTYPE_CONST = 3.141; template<> const char MyClass<char>::TTYPE_CONST = 'a'; So in this case, foo() will be documented as printing "Generic foo," INT_CONST will be documented as set to 5, with no mention of the specializations, and TTYPE_CONST will be documented as set to 'a', with no mention of 3.141 and no indication that 'a' is a specialized case. I need to be able to document the specializations - either within the documentation for MyClass<T>, or on new pages for MyClass<double>, MyClass<char>. How do I do this? Can Doxygen even handle this? Am I possibly doing something wrong in the declarations/code structure that's keeping Doxygen from understanding what I want? I should note two related cases: A) For templated functions, specialization works fine, e.g.: /* functions that are global/in a namespace */ template<class T> void foo(){ printf("Generic foo\n"); } template<> void foo<double>(){ printf("Specialized double foo\n"); } This will document both foo() and foo(). B) If I redeclare the entire template, i.e. template<> class MyClass<double>{...};, then MyClass<double> will get its own documentation page, as a seperate class. But this means actually declaring an entirely new class - there is no relation between MyClass<T> and MyClass<double> if MyClass<double> itself is declared. So I'd have to redeclare the class and all its members, and repeat all the definitions of class members, specialized for MyClass<double>, all to make it appear as though they're using the same template. Very awkward, feels like a kludge solution. Suggestions? Thanks much :) --Ziv

  Read the article

• Winforms controls and "generic" events handlers. How can I do this?

  - by Yanko Hernández Alvarez

  In the demo of the ObjectListView control there is this code (in the "Complex Example" tab page) to allow for a custom editor (a ComboBox) (Adapted to my case and edited for clarity): EventHandler CurrentEH; private void ObjectListView_CellEditStarting(object sender, CellEditEventArgs e) { if (e.Column == SomeCol) { ISomeInterface M = (e.RowObject as ObjectListView1Row).SomeObject; //(1) ComboBox cb = new ComboBox(); cb.Bounds = e.CellBounds; cb.DropDownStyle = ComboBoxStyle.DropDownList; cb.DataSource = ISomeOtherObjectCollection; cb.DisplayMember = "propertyName"; cb.DataBindings.Add("SelectedItem", M, "ISomeOtherObject", false, DataSourceUpdateMode.Never); e.Control = cb; cb.SelectedIndexChanged += CurrentEH = (object sender2, EventArgs e2) => M.ISomeOtherObject = (ISomeOtherObject)((ComboBox)sender2).SelectedValue; //(2) } } private void ObjectListView_CellEditFinishing(object sender, CellEditEventArgs e) { if (e.Column == SomeCol) { // Stop listening for change events ((ComboBox)e.Control).SelectedIndexChanged -= CurrentEH; // Any updating will have been down in the SelectedIndexChanged // event handler. // Here we simply make the list redraw the involved ListViewItem ((ObjectListView)sender).RefreshItem(e.ListViewItem); // We have updated the model object, so we cancel the auto update e.Cancel = true; } } I have too many other columns with combo editors inside objectlistviews to use a copy& paste strategy (besides, copy&paste is a serious source of bugs), so I tried to parameterize the code to keep the code duplication to a minimum. ObjectListView_CellEditFinishing is a piece of cake: HashSet<OLVColumn> cbColumns = new HashSet<OLVColumn> (new OLVColumn[] { SomeCol, SomeCol2, ...}; private void ObjectListView_CellEditFinishing(object sender, CellEditEventArgs e) { if (cbColumns.Contains(e.Column)) ... but ObjectListView_CellEditStarting is the problematic. I guess in CellEditStarting I will have to discriminate each case separately: private void ObjectListView_CellEditStarting(object sender, CellEditEventArgs e) { if (e.Column == SomeCol) // code to create the combo, put the correct list as the datasource, etc. else if (e.Column == SomeOtherCol) // code to create the combo, put the correct list as the datasource, etc. And so on. But how can I parameterize the "code to create the combo, put the correct list as the datasource, etc."? Problem lines are (1) Get SomeObject. the property NAME varies. (2) Set ISomeOtherObject, the property name varies too. The types vary too, but I can cover those cases with a generic method combined with a not so "typesafe" API (for instance, the cb.DataBindings.Add and cb.DataSource both use an object) Reflection? more lambdas? Any ideas? Any other way to do the same? PS: I want to be able to do something like this: private void ObjectListView_CellEditStarting(object sender, CellEditEventArgs e) { if (e.Column == SomeCol) SetUpCombo<ISomeInterface>(ISomeOtherObjectCollection, "propertyName", SomeObject, ISomeOtherObject); else if (e.Column == SomeOtherCol) SetUpCombo<ISomeInterface2>(ISomeOtherObject2Collection, "propertyName2", SomeObject2 ISomeOtherObject2); and so on. Or something like that. I know, parameters SomeObject and ISomeOtherObject are not real parameters per see, but you get the idea of what I want. I want not to repeat the same code skeleton again and again and again. One solution would be "preprocessor generics" like C's DEFINE, but I don't thing c# has something like that. So, does anyone have some alternate ideas to solve this?

  Read the article

• MySQL and INT auto_increment fields

  - by PHPguy

  Hello folks, I'm developing in LAMP (Linux+Apache+MySQL+PHP) since I remember myself. But one question was bugging me for years now. I hope you can help me to find an answer and point me into the right direction. Here is my challenge: Say, we are creating a community website, where we allow our users to register. The MySQL table where we store all users would look then like this: CREATE TABLE `users` ( `uid` int(2) unsigned NOT NULL auto_increment COMMENT 'User ID', `name` varchar(20) NOT NULL, `password` varchar(32) NOT NULL COMMENT 'Password is saved as a 32-bytes hash, never in plain text', `email` varchar(64) NOT NULL, `created` int(11) unsigned NOT NULL default '0' COMMENT 'Timestamp of registration', `updated` int(11) unsigned NOT NULL default '0' COMMENT 'Timestamp of profile update, e.g. change of email', PRIMARY KEY (`uid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; So, from this snippet you can see that we have a unique and automatically incrementing for every new user 'uid' field. As on every good and loyal community website we need to provide users with possibility to completely delete their profile if they want to cancel their participation in our community. Here comes my problem. Let's say we have 3 registered users: Alice (uid = 1), Bob (uid = 2) and Chris (uid = 3). Now Bob want to delete his profile and stop using our community. If we delete Bob's profile from the 'users' table then his missing 'uid' will create a gap which will be never filled again. In my opinion it's a huge waste of uid's. I see 3 possible solutions here: 1) Increase the capacity of the 'uid' field in our table from SMALLINT (int(2)) to, for example, BIGINT (int(8)) and ignore the fact that some of the uid's will be wasted. 2) introduce the new field 'is_deleted', which will be used to mark deleted profiles (but keep them in the table, instead of deleting them) to re-utilize their uid's for newly registered users. The table will look then like this: CREATE TABLE `users` ( `uid` int(2) unsigned NOT NULL auto_increment COMMENT 'User ID', `name` varchar(20) NOT NULL, `password` varchar(32) NOT NULL COMMENT 'Password is saved as a 32-bytes hash, never in plain text', `email` varchar(64) NOT NULL, `is_deleted` int(1) unsigned NOT NULL default '0' COMMENT 'If equal to "1" then the profile has been deleted and will be re-used for new registrations', `created` int(11) unsigned NOT NULL default '0' COMMENT 'Timestamp of registration', `updated` int(11) unsigned NOT NULL default '0' COMMENT 'Timestamp of profile update, e.g. change of email', PRIMARY KEY (`uid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; 3) Write a script to shift all following user records once a previous record has been deleted. E.g. in our case when Bob (uid = 2) decides to remove his profile, we would replace his record with the record of Chris (uid = 3), so that uid of Chris becomes qual to 2 and mark (is_deleted = '1') the old record of Chris as vacant for the new users. In this case we keep the chronological order of uid's according to the registration time, so that the older users have lower uid's. Please, advice me now which way is the right way to handle the gaps in the auto_increment fields. This is just one example with users, but such cases occur very often in my programming experience. Thanks in advance!

  Read the article

• Anything wrong with this function for comparing floats?

  - by Michael Borgwardt

  When my Floating-Point Guide was yesterday published on slashdot, I got a lot of flak for my suggested comparison function, which was indeed inadequate. So I finally did the sensible thing and wrote a test suite to see whether I could get them all to pass. Here is my result so far. And I wonder if this is really as good as one can get with a generic (i.e. not application specific) float comparison function, or whether I still missed some edge cases. import static org.junit.Assert.assertFalse; import static org.junit.Assert.assertTrue; import org.junit.Test; public class NearlyEqualsTest { public static boolean nearlyEqual(float a, float b) { final float epsilon = 0.000001f; final float absA = Math.abs(a); final float absB = Math.abs(b); final float diff = Math.abs(a-b); if (a*b==0) { // a or b or both are zero // relative error is not meaningful here return diff < Float.MIN_VALUE / epsilon; } else { // use relative error return diff / (absA+absB) < epsilon; } } /** Regular large numbers - generally not problematic */ @Test public void big() { assertTrue(nearlyEqual(1000000f, 1000001f)); assertTrue(nearlyEqual(1000001f, 1000000f)); assertFalse(nearlyEqual(10000f, 10001f)); assertFalse(nearlyEqual(10001f, 10000f)); } /** Negative large numbers */ @Test public void bigNeg() { assertTrue(nearlyEqual(-1000000f, -1000001f)); assertTrue(nearlyEqual(-1000001f, -1000000f)); assertFalse(nearlyEqual(-10000f, -10001f)); assertFalse(nearlyEqual(-10001f, -10000f)); } /** Numbers around 1 */ @Test public void mid() { assertTrue(nearlyEqual(1.0000001f, 1.0000002f)); assertTrue(nearlyEqual(1.0000002f, 1.0000001f)); assertFalse(nearlyEqual(1.0002f, 1.0001f)); assertFalse(nearlyEqual(1.0001f, 1.0002f)); } /** Numbers around -1 */ @Test public void midNeg() { assertTrue(nearlyEqual(-1.000001f, -1.000002f)); assertTrue(nearlyEqual(-1.000002f, -1.000001f)); assertFalse(nearlyEqual(-1.0001f, -1.0002f)); assertFalse(nearlyEqual(-1.0002f, -1.0001f)); } /** Numbers between 1 and 0 */ @Test public void small() { assertTrue(nearlyEqual(0.000000001000001f, 0.000000001000002f)); assertTrue(nearlyEqual(0.000000001000002f, 0.000000001000001f)); assertFalse(nearlyEqual(0.000000000001002f, 0.000000000001001f)); assertFalse(nearlyEqual(0.000000000001001f, 0.000000000001002f)); } /** Numbers between -1 and 0 */ @Test public void smallNeg() { assertTrue(nearlyEqual(-0.000000001000001f, -0.000000001000002f)); assertTrue(nearlyEqual(-0.000000001000002f, -0.000000001000001f)); assertFalse(nearlyEqual(-0.000000000001002f, -0.000000000001001f)); assertFalse(nearlyEqual(-0.000000000001001f, -0.000000000001002f)); } /** Comparisons involving zero */ @Test public void zero() { assertTrue(nearlyEqual(0.0f, 0.0f)); assertFalse(nearlyEqual(0.00000001f, 0.0f)); assertFalse(nearlyEqual(0.0f, 0.00000001f)); } /** Comparisons of numbers on opposite sides of 0 */ @Test public void opposite() { assertFalse(nearlyEqual(1.000000001f, -1.0f)); assertFalse(nearlyEqual(-1.0f, 1.000000001f)); assertFalse(nearlyEqual(-1.000000001f, 1.0f)); assertFalse(nearlyEqual(1.0f, -1.000000001f)); assertTrue(nearlyEqual(10000f*Float.MIN_VALUE, -10000f*Float.MIN_VALUE)); } /** * The really tricky part - comparisons of numbers * very close to zero. */ @Test public void ulp() { assertTrue(nearlyEqual(Float.MIN_VALUE, -Float.MIN_VALUE)); assertTrue(nearlyEqual(-Float.MIN_VALUE, Float.MIN_VALUE)); assertTrue(nearlyEqual(Float.MIN_VALUE, 0)); assertTrue(nearlyEqual(0, Float.MIN_VALUE)); assertTrue(nearlyEqual(-Float.MIN_VALUE, 0)); assertTrue(nearlyEqual(0, -Float.MIN_VALUE)); assertFalse(nearlyEqual(0.000000001f, -Float.MIN_VALUE)); assertFalse(nearlyEqual(0.000000001f, Float.MIN_VALUE)); assertFalse(nearlyEqual(Float.MIN_VALUE, 0.000000001f)); assertFalse(nearlyEqual(-Float.MIN_VALUE, 0.000000001f)); assertFalse(nearlyEqual(1e20f*Float.MIN_VALUE, 0.0f)); assertFalse(nearlyEqual(0.0f, 1e20f*Float.MIN_VALUE)); assertFalse(nearlyEqual(1e20f*Float.MIN_VALUE, -1e20f*Float.MIN_VALUE)); } }

  Read the article

• Are there supposed to be more restrictions on operator->* overloads?

  - by Potatoswatter

  I was perusing section 13.5 after refuting the notion that built-in operators do not participate in overload resolution, and noticed that there is no section on operator->*. It is just a generic binary operator. Its brethren, operator->, operator*, and operator[], are all required to be non-static member functions. This precludes definition of a free function overload to an operator commonly used to obtain a reference from an object. But the uncommon operator->* is left out. In particular, operator[] has many similarities. It is binary (they missed a golden opportunity to make it n-ary), and it accepts some kind of container on the left and some kind of locator on the right. Its special-rules section, 13.5.5, doesn't seem to have any actual effect except to outlaw free functions. (And that restriction even precludes support for commutativity!) So, for example, this is perfectly legal (in C++0x, remove obvious stuff to translate to C++03): #include <utility> #include <iostream> #include <type_traits> using namespace std; template< class F, class S > typename common_type< F,S >::type operator->*( pair<F,S> const &l, bool r ) { return r? l.second : l.first; } template< class T > T & operator->*( pair<T,T> &l, bool r ) { return r? l.second : l.first; } template< class T > T & operator->*( bool l, pair<T,T> &r ) { return l? r.second : r.first; } int main() { auto x = make_pair( 1, 2.3 ); cerr << x->*false << " " << x->*4 << endl; auto y = make_pair( 5, 6 ); y->*(0) = 7; y->*0->*y = 8; // evaluates to 7->*y = y.second cerr << y.first << " " << y.second << endl; } I can certainly imagine myself giving into temp[la]tation. For example, scaled indexes for vector: v->*matrix_width[5] = x; Did the standards committee forget to prevent this, was it considered too ugly to bother, or are there real-world use cases?

  Read the article

• window.open() in an iPad on load of a frame does not work

  - by user278859

  I am trying to modify a site that uses "Morten's JavaScript Tree Menu" to display PDFs in a frames set using the Adobe Reader plug-in. On the iPad the frame is useless, so I want to open the PDF in a new tab. Not wanting to mess with the tree menu I thought I could use JavaScript in the web page being opened in the viewer frame to open a new tab with the PDF. I am using window.open() in $(document).ready(function() to open the pdf in the new tab. The problem is that window.open() does not want to work in the iPad. The body of the HTML normally looks like this... <body> <object data="MypdfFileName.pdf#toolbar=1&amp;navpanes=1&amp;scrollbar=0&amp;page=1&amp;view=FitH" type="application/pdf" width="100%" height="100%"> </object> </body> I changed it to only have a div like this... <body> <div class="myviewer" ></div> </body> Then used the following script... $(document).ready(function() { var isMobile = { Android : function() { return navigator.userAgent.match(/Android/i) ? true : false; }, BlackBerry : function() { return navigator.userAgent.match(/BlackBerry/i) ? true : false; }, iOS : function() { return navigator.userAgent.match(/iPhone|iPad|iPod/i) ? true : false; }, Windows : function() { return navigator.userAgent.match(/IEMobile/i) ? true : false; }, any : function() { return (isMobile.Android() || isMobile.BlackBerry() || isMobile.iOS() || isMobile.Windows()); } }; if(isMobile.any()) { var file = "MypdfFileName.pdf"; window.open(file); }else { var markup = "<object data='MypdfFileName.pdf#toolbar=1&amp;navpanes=1&amp;scrollbar=0&amp;page=1&amp;view=FitH' type='application/pdf' width='100%' height='100%'></object>"; $('.myviewer').append(markup); }; }); Everthing works except for window.open() on the iPad. If I switch things around widow.open() works fine on a computer. In another project I am using window.open() successfully on the iPad from an onclick function. I tried using a timer function. I also tried adding an onclick function to the div and posting a click event. In both cases they worked on a computer but not an iPad. I am stumped. I know it would make more sense to handle the ipad in the tree menu frame, but that code is so complex I can't figure out where to put/modify the onclick event. Is there a way to change the object so that it opens in a new tab? Is anyone familiar enough with Mortens Tree Menu code that can tell me how to channge the on click event so that it opens the pdf in a new tab instead of opening a page in the frame? Thanks

  Read the article

• Converting OCaml to F#: F# equivelent of Pervasives at_exit

  - by Guy Coder

  I am converting the OCaml Format module to F# and tracked a problem back to a use of the OCaml Pervasives at_exit. val at_exit : (unit -> unit) -> unit Register the given function to be called at program termination time. The functions registered with at_exit will be called when the program executes exit, or terminates, either normally or because of an uncaught exception. The functions are called in "last in, first out" order: the function most recently added with at_exit is called first. In the process of conversion I commented out the line as the compiler did not flag it as being needed and I was not expecting an event in the code. I checked the FSharp.PowerPack.Compatibility.PervasivesModule for at_exit using VS Object Browser and found none. I did find how to run code "at_exit"? and How do I write an exit handler for an F# application? The OCaml line is at_exit print_flush with print_flush signature: val print_flush : (unit -> unit) Also in looking at the use of it during a debug session of the OCaml code, it looks like at_exit is called both at the end of initialization and at the end of each use of a call to the module. Any suggestions, hints on how to do this. This will be my first event in F#. EDIT Here is some of what I have learned about the Format module that should shed some light on the problem. The Format module is a library of functions for basic pretty printer commands of simple OCaml values such as int, bool, string. The format module has commands like print_string, but also some commands to say put the next line in a bounded box, think new set of left and right margins. So one could write: print_string "Hello" or open_box 0; print_string "<<"; open_box 0; print_string "p \/ q ==> r"; close_box(); print_string ">>"; close_box() The commands such as open_box and print_string are handled by a loop that interprets the commands and then decides wither to print on the current line or advance to the next line. The commands are held in a queue and there is a state record to hold mutable values such as left and right margin. The queue and state needs to be primed, which from debugging the test cases against working OCaml code appears to be done at the end of initialization of the module but before the first call is made to any function in the Format module. The queue and state is cleaned up and primed again for the next set of commands by the use of mechanisms for at_exit that recognize that the last matching frame for the initial call to the format modules has been removed thus triggering the call to at_exit which pushes out any remaining command in the queue and re-initializes the queue and state. So the sequencing of the calls to print_flush is critical and appears to be at more than what the OCaml documentation states.

  Read the article

• Different cursor formats in IOFrameBufferShared

  - by Thomi

  Hi, I'm reading the moust cursor pixmap data from the StdFBShmem_t structure, as defined in the IOFrameBufferShared API. Everything works fine, 90% of the time. However, I have noticed that some applications on the mac set a cursor in a different format. According to the documentation for the data structures, the cursor pixmap format should always be in the same format as the frame buffer. My frame buffer is 32BPP. I expect the pixmap data to be in the format 0xAARRGGBB, which is it. However, in some cases, I'm reading data that looks like a mask. Specifically, the pixel will either be 0x00FFFFFF or `0x00000000. This looks to me to be a mask for separate pixel data stored somewhere else. As far as I can tell, the only application that uses this cursor pixel format is Qt Creator, but I need to work with all applications, so I'd like to sort this out. The code I'm using to read the cursor pixmap data is: NSAutoreleasePool *autoReleasePool = [[NSAutoreleasePool alloc] init]; NSPoint mouseLocation = [NSEvent mouseLocation]; NSArray *allScreens = [NSScreen screens]; NSEnumerator *screensEnum = [allScreens objectEnumerator]; NSScreen *screen; NSDictionary *screenDesc = nil; while ((screen = [screensEnum nextObject])) { NSRect screenFrame = [screen frame]; screenDesc = [screen deviceDescription]; if (NSMouseInRect(mouseLocation, screenFrame, NO)) break; } if (screen) { kern_return_t err; CGDirectDisplayID displayID = (CGDirectDisplayID) [[screenDesc objectForKey:@"NSScreenNumber"] pointerValue]; task_port_t taskPort = mach_task_self(); io_service_t displayServicePort = CGDisplayIOServicePort(displayID); io_connect_t displayConnection =0; err = IOFramebufferOpen(displayServicePort, taskPort, kIOFBSharedConnectType, &displayConnection); if (KERN_SUCCESS == err) { union { vm_address_t vm_ptr; StdFBShmem_t *fbshmem; } cursorInfo; vm_size_t size; err = IOConnectMapMemory(displayConnection, kIOFBCursorMemory, taskPort, &cursorInfo.vm_ptr, &size, kIOMapAnywhere | kIOMapDefaultCache | kIOMapReadOnly); if (KERN_SUCCESS == err) { // for some reason, cursor data is not always in the same format as the frame buffer. For this reason, we need // some way to detect which structure we should be reading. QByteArray pixData((const char*)cursorInfo.fbshmem->cursor.rgb24.image[currentFrame], m_mouseInfo.currentSize.width() * m_mouseInfo.currentSize.height() * 4); IOConnectUnmapMemory(displayConnection, kIOFBCursorMemory, taskPort, cursorInfo.vm_ptr); } // IOConnectMapMemory else qDebug() << "IOConnectMapMemory Failed:" << err; IOServiceClose(displayConnection); } // IOServiceOpen else qDebug() << "IOFramebufferOpen Failed:" << err; }// if screen [autoReleasePool release]; My question is: How can I detect if the cursor is a different format from the framebuffer? Where can I read the actual pixel data? the bm18Cursor structure contains a mask section, but it's not in the right place for me to be reading it using the code above. Cheers,

  Read the article

• Game logic dynamically extendable architecture implementation patterns

  - by Vlad

  When coding games there are a lot of cases when you need to inject your logic into existing class dynamically and without making unnecessary dependencies. For an example I have a Rabbit which can be affected by freeze ability so it can't jump. It could be implemented like this: class Rabbit { public bool CanJump { get; set; } void Jump() { if (!CanJump) return; ... } } But If I have more than one ability that can prevent it from jumping? I can't just set one property because some circumstances can be activated simultanously. Another solution? class Rabbit { public bool Frozen { get; set; } public bool InWater { get; set; } bool CanJump { get { return !Frozen && !InWater; } } } Bad. The Rabbit class can't know all the circumstances it can run into. Who knows what else will game designer want to add: may be an ability that changes gravity on an area? May be make a stack of bool values for CanJump property? No, because abilities can be deactivated not in that order in which they were activated. I need a way to seperate ability logic that prevent the Rabbit from jumping from the Rabbit itself. One possible solution for this is making special checking event: class Rabbit { class CheckJumpEventArgs : EventArgs { public bool Veto { get; set; } } public event EventHandler<CheckJumpEvent> OnCheckJump; void Jump() { var args = new CheckJumpEventArgs(); if (OnCheckJump != null) OnCheckJump(this, args); if (!args.Veto) return; ... } } But it's a lot of code! A real Rabbit class would have a lot of properties like this (health and speed attributes, etc). I'm thinking of borrowing something from MVVM pattern where you have all the properties and methods of an object implemented in a way where they can be easily extended from outside. Then I want to use it like this: class FreezeAbility { void ActivateAbility() { _rabbit.CanJump.Push(ReturnFalse); } void DeactivateAbility() { _rabbit.CanJump.Remove(ReturnFalse); } // should be implemented as instance member // so it can be "unsubscribed" bool ReturnFalse(bool previousValue) { return false; } } Is this approach good? What also should I consider? What are other suitable options and patterns? Any ready to use solutions? UPDATE The question is not about how to add different behaviors to an object dynamically but how its (or its behavior) implementation can be extended with external logic. I don't need to add a different behavior but I need a way to modify an exitsing one and I also need a possibiliity to undo changes.

  Read the article

• Strange performance behaviour for 64 bit modulo operation

  - by codymanix

  The last three of these method calls take approx. double the time than the first four. The only difference is that their arguments doesn't fit in integer anymore. But should this matter? The parameter is declared to be long, so it should use long for calculation anyway. Does the modulo operation use another algorithm for numbersmaxint? I am using amd athlon64 3200+, winxp sp3 and vs2008. Stopwatch sw = new Stopwatch(); TestLong(sw, int.MaxValue - 3l); TestLong(sw, int.MaxValue - 2l); TestLong(sw, int.MaxValue - 1l); TestLong(sw, int.MaxValue); TestLong(sw, int.MaxValue + 1l); TestLong(sw, int.MaxValue + 2l); TestLong(sw, int.MaxValue + 3l); Console.ReadLine(); static void TestLong(Stopwatch sw, long num) { long n = 0; sw.Reset(); sw.Start(); for (long i = 3; i < 20000000; i++) { n += num % i; } sw.Stop(); Console.WriteLine(sw.Elapsed); } EDIT: I now tried the same with C and the issue does not occur here, all modulo operations take the same time, in release and in debug mode with and without optimizations turned on: #include "stdafx.h" #include "time.h" #include "limits.h" static void TestLong(long long num) { long long n = 0; clock_t t = clock(); for (long long i = 3; i < 20000000LL*100; i++) { n += num % i; } printf("%d - %lld\n", clock()-t, n); } int main() { printf("%i %i %i %i\n\n", sizeof (int), sizeof(long), sizeof(long long), sizeof(void*)); TestLong(3); TestLong(10); TestLong(131); TestLong(INT_MAX - 1L); TestLong(UINT_MAX +1LL); TestLong(INT_MAX + 1LL); TestLong(LLONG_MAX-1LL); getchar(); return 0; } EDIT2: Thanks for the great suggestions. I found that both .net and c (in debug as well as in release mode) does't not use atomically cpu instructions to calculate the remainder but they call a function that does. In the c program I could get the name of it which is "_allrem". It also displayed full source comments for this file so I found the information that this algorithm special cases the 32bit divisors instead of dividends which was the case in the .net application. I also found out that the performance of the c program really is only affected by the value of the divisor but not the dividend. Another test showed that the performance of the remainder function in the .net program depends on both the dividend and divisor. BTW: Even simple additions of long long values are calculated by a consecutive add and adc instructions. So even if my processor calls itself 64bit, it really isn't :( EDIT3: I now ran the c app on a windows 7 x64 edition, compiled with visual studio 2010. The funny thing is, the performance behavior stays the same, although now (I checked the assembly source) true 64 bit instructions are used.

  Read the article

• How to determine edges in an images optimally?

  - by SorinA.

  I recently was put in front of the problem of cropping and resizing images. I needed to crop the 'main content' of an image for example if i had an image similar to this: the result should be an image with the msn content without the white margins(left& right). I search on the X axis for the first and last color change and on the Y axis the same thing. The problem is that traversing the image line by line takes a while..for an image that is 2000x1600px it takes up to 2 seconds to return the CropRect = x1,y1,x2,y2 data. I tried to make for each coordinate a traversal and stop on the first value found but it didn't work in all test cases..sometimes the returned data wasn't the expected one and the duration of the operations was similar.. Any idea how to cut down the traversal time and discovery of the rectangle round the 'main content'? public static CropRect EdgeDetection(Bitmap Image, float Threshold) { CropRect cropRectangle = new CropRect(); int lowestX = 0; int lowestY = 0; int largestX = 0; int largestY = 0; lowestX = Image.Width; lowestY = Image.Height; //find the lowest X bound; for (int y = 0; y < Image.Height - 1; ++y) { for (int x = 0; x < Image.Width - 1; ++x) { Color currentColor = Image.GetPixel(x, y); Color tempXcolor = Image.GetPixel(x + 1, y); Color tempYColor = Image.GetPixel(x, y + 1); if ((Math.Sqrt(((currentColor.R - tempXcolor.R) * (currentColor.R - tempXcolor.R)) + ((currentColor.G - tempXcolor.G) * (currentColor.G - tempXcolor.G)) + ((currentColor.B - tempXcolor.B) * (currentColor.B - tempXcolor.B))) > Threshold)) { if (lowestX > x) lowestX = x; if (largestX < x) largestX = x; } if ((Math.Sqrt(((currentColor.R - tempYColor.R) * (currentColor.R - tempYColor.R)) + ((currentColor.G - tempYColor.G) * (currentColor.G - tempYColor.G)) + ((currentColor.B - tempYColor.B) * (currentColor.B - tempYColor.B))) > Threshold)) { if (lowestY > y) lowestY = y; if (largestY < y) largestY = y; } } } if (lowestX < Image.Width / 4) cropRectangle.X = lowestX - 3 > 0 ? lowestX - 3 : 0; else cropRectangle.X = 0; if (lowestY < Image.Height / 4) cropRectangle.Y = lowestY - 3 > 0 ? lowestY - 3 : 0; else cropRectangle.Y = 0; cropRectangle.Width = largestX - lowestX + 8 > Image.Width ? Image.Width : largestX - lowestX + 8; cropRectangle.Height = largestY + 8 > Image.Height ? Image.Height - lowestY : largestY - lowestY + 8; return cropRectangle; } }

  Read the article

• "didChangeSection:" NSfetchedResultsController delegate method not being called

  - by robenk

  I have a standard split view controller, with a detail view and a table view. Pressing a button in the detail view can cause the an object to change its placement in the table view's ordering. This works fine, as long as the resulting ordering change doesn't result in a section being added or removed. I.e. an object can change it's ordering in a section or switch from one section to another. Those ordering changes work correctly without problems. But, if the object tries to move to a section that doesn't exist yet, or is the last object to leave a section (therefore requiring the section its leaving to be removed), then the application crashes. NSFetchedResultsControllerDelegate has methods to handle sections being added and removed that should be called in those cases. But those delegate methods aren't being called for some reason. The code in question, is boilerplate: - (void)controllerWillChangeContent:(NSFetchedResultsController *)controller { NSLog(@"willChangeContent"); [self.tableView beginUpdates]; } - (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type { NSLog(@"didChangeSection"); switch(type) { case NSFetchedResultsChangeInsert: [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade]; break; case NSFetchedResultsChangeDelete: [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade]; break; } } - (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath { NSLog(@"didChangeObject"); UITableView *tableView = self.tableView; switch(type) { case NSFetchedResultsChangeInsert: [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade]; break; case NSFetchedResultsChangeDelete: [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; break; case NSFetchedResultsChangeUpdate: [self configureCell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath]; break; case NSFetchedResultsChangeMove: [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]withRowAnimation:UITableViewRowAnimationFade]; break; } } - (void)controllerDidChangeContent:(NSFetchedResultsController *)controller { NSLog(@"didChangeContent"); [self.tableView endUpdates]; [detailViewController.reminderView update]; } Starting the application, and then causing the last object to leave a section results in the following output: 2011-01-08 23:40:18.910 Reminders[54647:207] willChangeContent 2011-01-08 23:40:18.912 Reminders[54647:207] didChangeObject 2011-01-08 23:40:18.914 Reminders[54647:207] didChangeContent 2011-01-08 23:40:18.915 Reminders[54647:207] *** Assertion failure in -[UITableView _endCellAnimationsWithContext:], /SourceCache/UIKit_Sim/UIKit-1145.66/UITableView.m:825 2011-01-08 23:40:18.917 Reminders[54647:207] Serious application error. Exception was caught during Core Data change processing: Invalid update: invalid number of sections. The number of sections contained in the table view after the update (5) must be equal to the number of sections contained in the table view before the update (6), plus or minus the number of sections inserted or deleted (0 inserted, 0 deleted). with userInfo (null) As you can see, "willChangeContent", "didChangeObject" (moving the object in question), and "didChangeContent" were all called properly. Based on the Apple's NSFetchedResultsControllerDelegate documentation "didChangeSection" should have been called before "didChangeObject", which would have prevented the exception causing the crash. So I guess the question is how do I assure that didChangeSection gets called? Thanks in advance for any help!

  Read the article

• T60 Screen/LCD gets black after some minutes with a highpitched sound rising and fading

  - by edelwater

  Just now my T60 screen got "black" (so no display). On my second monitor: no problems so the VGA output works. Symptom: Screen blanks / no display, but it works on the second monitor Steps to reproduce: - boot - wait (it does not matter what you do you do not have to login or anything) - (now the monitor of the laptop slowly begins to make a ssssssssHHHHHHHHHHHHHHHHHWOEOEssssssss noise of about 10 seconds) - right after the sounds ends, the monitor gets black. Sometimes it seems to be the same each time. Software: Installed no new software before/after, running ZoneAlarm and antivirus. Other: It does not feel hot in any place, there don't seem to be running processes with strange behaviour. Warranty: Out of warranty What was I doing: Typing text on a website and doing some PHP coding in a text editor. What can I do here other than buy a new laptop? Does it sound familiar to known cases? Update 1: Exactly the same problem: http://forums.lenovo.com/t5/T61-and-prior-T-series-ThinkPad/T60-Screen-Blackout/m-p/288772 and the second poster (garyj), http://forums.lenovo.com/t5/T61-and-prior-T-series-ThinkPad/Black-Screen-on-T60/m-p/235053#M48627 And here: "I have that same problem. I replaced the CCRL on mine and it works fine when the screen is not screwed in. Once the frame of the LCD screen (metal portion) touches the metal on the laptop which holds the screen the screen goes black. If the metal is touching the screen when you boot up it boots up with it being very dimmly lit. " from http://forums.lenovo.com/t5/T61-and-prior-T-series-ThinkPad/T60-screen-problems/m-p/205047#M44995 (it seems replacing the LCD display is no use, he tried it three times). Same problem: http://forums.lenovo.com/t5/T61-and-prior-T-series-ThinkPad/T60-black-screen/m-p/80604#M25914 Hmmm... not handy 3 or 4 months ago I ordered and installed a new fan. Now the LCD. Which does not seem the core issue but some electric issue so it seems replacing the LCD is not the thing to do here. If it is not the LCD that needs to be replaced (see other threads), which parts can I order to fix this? Is there any information which could lead me to identify the issue? I have read replacing the "inverter" AND the "backlightning" would that make sense? Update 2: I replaced the inverter with another inverter, but IO have the same problem. I DID notice that the inverter is the component that makes the sssssssssssssHHHHHHHHHH sound AND it becomes very hot in a few seconds. (So both the old and the test one) The problem is hmmm wat is then the thing that makes the inverter hot by (assumption) after which it shuts itself down. Is it either the input or the output? The output seems to me not, because the screen seems to function so it must be the electricity coming in. But what causes it to become so hot would it be the VGA card outputting some unusual high voltage seems unlikely? I am looking for the component to order / replace update 3: Great news. Ewendish gave me the hint to look in the BIOS. While I was in the BIOS I noticed that the screen did not switch off and there was not a high pitched sound. So I lowered some settings in the BIOS. I then noticed that with brightness turned to 0 (via FN End), it does not make a high pitched sound and does not turn off, with brightness turned up just three "stripes" it starts making the sound. So I could from now on work under lowest brightness modus or... see where the problem lies. So as stated below with either power management or display drivers / ATI Catalyst settings / Windows display settings. I'm trying to see where it lies, but I will google some first. Update 4: I wiped clean the Windows XP installation and installed Windows 7 on it. Unfortunately the problem remains: as soon as the brightness goes up the screen starts hissing. This means... back to original thought: it probably IS a hardware problem. Although ... again... if it is NOT the inverter, what is it? Could it be the backlightning component? I could try to switch that with a another T60... but this is quite tricky.

  Read the article

• Insert a transformed integer_sequence into a variadic template argument?

  - by coderforlife

  How do you insert a transformed integer_sequence (or similar since I am targeting C++11) into a variadic template argument? For example I have a class that represents a set of bit-wise flags (shown below). It is made using a nested-class because you cannot have two variadic template arguments for the same class. It would be used like typedef Flags<unsigned char, FLAG_A, FLAG_B, FLAG_C>::WithValues<0x01, 0x02, 0x04> MyFlags. Typically, they will be used with the values that are powers of two (although not always, in some cases certain combinations would be made, for example one could imagine a set of flags like Read=0x1, Write=0x2, and ReadWrite=0x3=0x1|0x2). I would like to provide a way to do typedef Flags<unsigned char, FLAG_A, FLAG_B, FLAG_C>::WithDefaultValues MyFlags. template<class _B, template <class,class,_B> class... _Fs> class Flags { public: template<_B... _Vs> class WithValues : public _Fs<_B, Flags<_B,_Fs...>::WithValues<_Vs...>, _Vs>... { // ... }; }; I have tried the following without success (placed inside the Flags class, outside the WithValues class): private: struct _F { // dummy class which can be given to a flag-name template template <_B _V> inline constexpr explicit _F(std::integral_constant<_B, _V>) { } }; // we count the flags, but only in a dummy way static constexpr unsigned _count = sizeof...(_Fs<_B, _F, 1>); static inline constexpr _B pow2(unsigned exp, _B base = 2, _B result = 1) { return exp < 1 ? result : pow2(exp/2, base*base, (exp % 2) ? result*base : result); } template <_B... _Is> struct indices { using next = indices<_Is..., sizeof...(_Is)>; using WithPow2Values = WithValues<pow2(_Is)...>; }; template <unsigned N> struct build_indices { using type = typename build_indices<N-1>::type::next; }; template <> struct build_indices<0> { using type = indices<>; }; //// Another attempt //template < _B... _Is> struct indices { // using WithPow2Values = WithValues<pow2(_Is)...>; //}; //template <unsigned N, _B... _Is> struct build_indices // : build_indices<N-1, N-1, _Is...> { }; //template < _B... _Is> struct build_indices<0, _Is...> // : indices<_Is...> { }; public: using WithDefaultValues = typename build_indices<_count>::type::WithPow2Values; Of course, I would be willing to have any other alternatives to the whole situation (supporting both flag names and values in the same template set, etc). I have included a "working" example at ideone: http://ideone.com/NYtUrg - by "working" I mean compiles fine without using default values but fails with default values (there is a #define to switch between them). Thanks!

  Read the article

• How to develop an english .com domain value rating algorithm?

  - by Tom

  I've been thinking about an algorithm that should rougly be able to guess the value of an english .com domain in most cases. For this to work I want to perform tests that consider the strengths and weaknesses of an english .com domain. A simple point based system is what I had in mind, where each domain property can be given a certain weight to factor it's importance in. I had these properties in mind: domain character length Eg. initially 20 points are added. If the domain has 4 or less characters, no points are substracted. For each extra character, one or more points are substracted on an exponential basis (the more characters, the higher the penalty). domain characters Eg. initially 20 points are added. If the domain is only alphabetic, no points are substracted. For each non-alhabetic character, X points are substracted (exponential increase again). domain name words Scans through a big offline english database, including non-formal speech, eg. words like "tweet" should be recognized. Question 1 : where can I get a modern list of english words for use in such application? Are these lists available for free? Are there lists like these with non-formal words? The more words are found per character, the more points are added. So, a domain with a lot of characters will still not get a lot of points. words hype-level I believe this is a tricky one, but this should be the cause to differentiate perfect but boring domains from perfect and interesting domains. For example, the following domain is probably not that valueable: www.peanutgalaxy.com The algorithm should identify that peanuts and galaxies are not very popular topics on the web. This is just an example. On the other side, a domain like www.shopdeals.com should ring a bell to the hype test, as shops and deals are quite popular on the web. My initial thought would be to see how often these keywords are references to on the web, preferably with some database. Question 2: is this logic flawed, or does this hype level test have merit? Question 3: are such "hype databases" available? Or is there anything else that could work offline? The problem with eg. a query to google is that it requires a lot of requests due to the many domains to be tested. domain name spelling mistakes Domains like "freemoneyz.com" etc. are generally (notice I am making a lot of assumptions in this post but that's necessary I believe) not valueable due to the spelling mistakes. Question 4: are there any offline APIs available to check for spelling mistakes, preferably in javascript or some database that I can use interact with myself. Or should a word list help here as well? use of consonants, vowels etc. A domain that is easy to pronounce (eg. Google) is usually much more valueable than one that is not (eg. Gkyld). Question 5: how does one test for such pronuncability? Do you check for consonants, vowels, etc.? What does a valueable domain have? Has there been any work in this field, where should I look? That is what I came up with, which leads me to my final two questions. Question 6: can you think of any more english .com domain strengths or weaknesses? Which? How would you implement these? Question 7: do you believe this idea has any merit or all, or am I too naive? Anything I should know, read or hear about? Suggestions/comments? Thanks!

  Read the article

• Linked Lists in Java - Help with assignment

  - by doron2010

  I have been trying to solve this assignment all day, please help me. I'm completely lost. Representation of a string in linked lists In every intersection in the list there will be 3 fields : The letter itself. The number of times it appears consecutively. A pointer to the next intersection in the list. The following class CharNode represents a intersection in the list : public class CharNode { private char _data; private int _value; private charNode _next; public CharNode (char c, int val, charNode n) { _data = c; _value = val; _next = n; } public charNode getNext() { return _next; } public void setNext (charNode node) { _next = node; } public int getValue() { return _value; } public void setValue (int v) { value = v; } public char getData() { return _data; } public void setData (char c) { _data = c; } } The class StringList represents the whole list : public class StringList { private charNode _head; public StringList() { _head = null; } public StringList (CharNode node) { _head = node; } } Add methods to the class StringList according to the details : (Pay attention, these are methods from the class String and we want to fulfill them by the representation of a string by a list as explained above) public char charAt (int i) - returns the char in the place i in the string. Assume that the value of i is in the right range. public StringList concat (String str) - returns a string that consists of the string that it is operated on and in its end the string "str" is concatenated. public int indexOf (int ch) - returns the index in the string it is operated on of the first appeareance of the char "ch". If the char "ch" doesn't appear in the string, returns -1. If the value of fromIndex isn't in the range, returns -1. public int indexOf (int ch, int fromIndex) - returns the index in the string it is operated on of the first appeareance of the char "ch", as the search begins in the index "fromIndex". If the char "ch" doesn't appear in the string, returns -1. public boolean equals (String str) - returns true if the string that it is operated on is equal to the string str. Otherwise returns false. This method must be written in recursion, without using loops at all. public int compareTo (String str) - compares between the string that the method is operated on to the string "str" that is in the parameter. The method returns 0 if the strings are equal. If the string in the object is smaller lexicographic from the string "str" in the paramater, a negative number will be returned. And if the string in the object is bigger lexicographic from the string "str", a positive number will be returned. public StringList substring (int i) - returns the list of the substring that starts in the place i in the string on which it operates. Meaning, the sub-string from the place i until the end of the string. Assume the value of i is in the right range. public StringList substring (int i, int j) - returns the list of the substring that begins in the place i and ends in the place j (not included) in the string it operates on. Assume the values of i, j are in the right range. public int length() - will return the length of the string on which it operates. Pay attention to all the possible error cases. Write what is the time complexity and space complexity of every method that you wrote. Make sure the methods you wrote are effective. It is NOT allowed to use ready classes of Java. It is NOT allowed to move to string and use string operations.

  Read the article

< Previous Page | 194 195 196 197 198 199 200 201 202 203 204 205  | Next Page >