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  • Pointers in C vs No pointers in PHP

    - by AnnaBanana
    Both languages have the same syntax. Why does C have the weird * character that denotes pointers (which is some kind of memory address of the variable contents?), when PHP doesn't have it and you can do pretty much the same things in PHP that you can do in C, without pointers? I guess the PHP compiler handles this internally, why doesn't C do the same? Doesn't this add unneeded complexity in C? For example I don't understand them :)

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  • null pointers vs. Null Object Pattern

    - by GlenH7
    Attribution: This grew out of a related P.SE question My background is in C / C++, but I have worked a fair amount in Java and am currently coding C#. Because of my C background, checking passed and returned pointers is second-hand, but I acknowledge it biases my point of view. I recently saw mention of the Null Object Pattern where the idea is than an object is always returned. Normal case returns the expected, populated object and the error case returns empty object instead of a null pointer. The premise being that the calling function will always have some sort of object to access and therefore avoid null access memory violations. So what are the pros / cons of a null check versus using the Null Object Pattern? I can see cleaner calling code with the NOP, but I can also see where it would create hidden failures that don't otherwise get raised. I would rather have my application fail hard (aka an exception) while I'm developing it than have a silent mistake escape into the wild. Can't the Null Object Pattern have similar problems as not performing a null check? Many of the objects I have worked with hold objects or containers of their own. It seems like I would have to have a special case to guarantee all of the main object's containers had empty objects of their own. Seems like this could get ugly with multiple layers of nesting.

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  • C++ Pointers: Number of levels of Indirection

    - by A B
    In a C++ program that doesn't contain legacy C code, is there a guideline regarding the maximum number of levels of indirection that should be used in the source code? I know that in C (as opposed to C++), some programmers have used pointers to pointers for a multiple dimension array, but for the case of arrays, there are data structures in C++ that can be used to avoid the pointers to pointers. Are users who still create pointers to pointers (or more than this) trying to use pointers to pointers only for performance ETC. reasons? I have tried NOT to use any more than a pointer to a pointer, only in the case that a pointer needed modification; does anyone have any other official or unofficial guidelines or rules regarding the number of levels of indirection?

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  • How do I fix a noisy input device (Internal Mic)? snd_hda_intel - debug included

    - by hazrpg
    As the title says, I'm having trouble with a very noisy audio input device - the internal mic or any plugged in mics. So far I've narrowed it down to an problem in ALSA since my debug info is showing a lot of "null" values. Can anyone help? Debug Info: http://www.alsa-project.org/db/?f=e0c6fb7e10624bf7691aa2b405cf0d3968e56c63 Exert from the debug: model : (null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null),(null)

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  • C++ smart pointers: sharing pointers vs. sharing data

    - by Eli Bendersky
    In this insightful article, one of the Qt programmers tries to explain the different kinds of smart pointers Qt implements. In the beginning, he makes a distinction between sharing data and sharing the pointers themselves: First, let’s get one thing straight: there’s a difference between sharing pointers and sharing data. When you share pointers, the value of the pointer and its lifetime is protected by the smart pointer class. In other words, the pointer is the invariant. However, the object that the pointer is pointing to is completely outside its control. We don’t know if the object is copiable or not, if it’s assignable or not. Now, sharing of data involves the smart pointer class knowing something about the data being shared. In fact, the whole point is that the data is being shared and we don’t care how. The fact that pointers are being used to share the data is irrelevant at this point. For example, you don’t really care how Qt tool classes are implicitly shared, do you? What matters to you is that they are shared (thus reducing memory consumption) and that they work as if they weren’t. Frankly, I just don't undersand this explanation. There was a clarification plea in the article comments, but I didn't find the author's explanation sufficient. If you do understand this, please explain. What is this distinction, and how are other shared pointer classes (i.e. from boost or the new C++ standards) fit into this taxonomy? Thanks in advance

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  • What's a nice explanation for pointers?

    - by Macneil
    In your own studies (on your own, or for a class) did you have an "ah ha" moment when you finally, really understood pointers? Do you have an explanation you use for beginner programmers that seems particularly effective? For example, when beginners first encounter pointers in C, they might just add &s and *s until it compiles (as I myself once did). Maybe it was a picture, or a really well motivated example, that made pointers "click" for you or your student. What was it, and what did you try before that didn't seem to work? Were any topics prerequisites (e.g. structs, or arrays)? In other words, what was necessary to understand the meaning of &s and *, when you could use them with confidence? Learning the syntax and terminology or the use cases isn't enough, at some point the idea needs to be internalized. Update: I really like the answers so far; please keep them coming. There are a lot of great perspectives here, but I think many are good explanations/slogans for ourselves after we've internalized the concept. I'm looking for the detailed contexts and circumstances when it dawned on you. For example: I only somewhat understood pointers syntactically in C. I heard two of my friends explaining pointers to another friend, who asked why a struct was passed with a pointer. The first friend talked about how it needed to be referenced and modified, but it was just a short comment from the other friend where it hit me: "It's also more efficient." Passing 4 bytes instead of 16 bytes was the final conceptual shift I needed.

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  • Unity completely broken after upgrade to 12.10?

    - by NlightNFotis
    I am facing a very frustrating issue with my computer right now. I successfully upgraded to Ubuntu 12.10 this afternoon, but after the upgrade, the graphical user interface seems completely broken. To be more specific, I can not get the Unity bar to appear on the right. I have tried many things, including (but not limited to) purging and then reinstalling the fglrx drivers, apt-get install --reinstall ubuntu-desktop, apt-get install --reinstall unity, tried to remove the Xorg and Compiz configurations, checked to see if the Ubuntu Unity wall was enabled (it was) in ccsm, all to no avail. Could someone help me troubleshoot and essentially fix this issue? NOTE: This is the output when I try to enable unity via a terminal: compiz (core) - Info: Loading plugin: core compiz (core) - Info: Starting plugin: core unity-panel-service: no process found compiz (core) - Info: Loading plugin: reset compiz (core) - Error: Failed to load plugin: reset compiz (core) - Info: Loading plugin: ccp compiz (core) - Info: Starting plugin: ccp compizconfig - Info: Backend : gsettings compizconfig - Info: Integration : true compizconfig - Info: Profile : unity compiz (core) - Info: Loading plugin: composite compiz (core) - Info: Starting plugin: composite compiz (core) - Info: Loading plugin: opengl X Error of failed request: BadRequest (invalid request code or no such operation) Major opcode of failed request: 153 (GLX) Minor opcode of failed request: 19 (X_GLXQueryServerString) Serial number of failed request: 22 Current serial number in output stream: 22 compiz (core) - Info: Unity is not supported by your hardware. Enabling software rendering instead (slow). compiz (core) - Info: Starting plugin: opengl Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 compiz (core) - Error: Plugin initScreen failed: opengl compiz (core) - Error: Failed to start plugin: opengl compiz (core) - Info: Unloading plugin: opengl compiz (core) - Info: Loading plugin: decor compiz (core) - Info: Starting plugin: decor compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available compiz (decor) - Warn: requested a pixmap type decoration when compositing isn't available Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 compiz (core) - Info: Loading plugin: imgpng compiz (core) - Info: Starting plugin: imgpng compiz (core) - Info: Loading plugin: vpswitch compiz (core) - Info: Starting plugin: vpswitch compiz (core) - Info: Loading plugin: resize compiz (core) - Info: Starting plugin: resize Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 compiz (core) - Info: Loading plugin: compiztoolbox compiz (core) - Info: Starting plugin: compiztoolbox compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Info: Loading plugin: move compiz (core) - Info: Starting plugin: move compiz (core) - Info: Loading plugin: gnomecompat compiz (core) - Info: Starting plugin: gnomecompat compiz (core) - Info: Loading plugin: mousepoll compiz (core) - Info: Starting plugin: mousepoll compiz (core) - Info: Loading plugin: wall compiz (core) - Info: Starting plugin: wall compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Error: Plugin init failed: wall compiz (core) - Error: Failed to start plugin: wall compiz (core) - Info: Unloading plugin: wall compiz (core) - Info: Loading plugin: regex compiz (core) - Info: Starting plugin: regex compiz (core) - Info: Loading plugin: snap compiz (core) - Info: Starting plugin: snap compiz (core) - Info: Loading plugin: unitymtgrabhandles compiz (core) - Info: Starting plugin: unitymtgrabhandles compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Error: Plugin init failed: unitymtgrabhandles compiz (core) - Error: Failed to start plugin: unitymtgrabhandles compiz (core) - Info: Unloading plugin: unitymtgrabhandles compiz (core) - Info: Loading plugin: place compiz (core) - Info: Starting plugin: place compiz (core) - Info: Loading plugin: grid compiz (core) - Info: Starting plugin: grid Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 compiz (core) - Info: Loading plugin: animation compiz (core) - Info: Starting plugin: animation compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Error: Plugin init failed: animation compiz (core) - Error: Failed to start plugin: animation compiz (core) - Info: Unloading plugin: animation compiz (core) - Info: Loading plugin: fade compiz (core) - Info: Starting plugin: fade compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Error: Plugin init failed: fade compiz (core) - Error: Failed to start plugin: fade compiz (core) - Info: Unloading plugin: fade compiz (core) - Info: Loading plugin: session compiz (core) - Info: Starting plugin: session compiz (core) - Info: Loading plugin: expo compiz (core) - Info: Starting plugin: expo compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Error: Plugin init failed: expo compiz (core) - Error: Failed to start plugin: expo compiz (core) - Info: Unloading plugin: expo compiz (core) - Info: Loading plugin: ezoom compiz (core) - Info: Starting plugin: ezoom compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Error: Plugin init failed: ezoom compiz (core) - Error: Failed to start plugin: ezoom compiz (core) - Info: Unloading plugin: ezoom compiz (core) - Info: Loading plugin: workarounds compiz (core) - Info: Starting plugin: workarounds compiz (core) - Error: Plugin 'opengl' not loaded. Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 compiz (core) - Info: Loading plugin: scale compiz (core) - Info: Starting plugin: scale compiz (core) - Error: Plugin 'opengl' not loaded. compiz (core) - Error: Plugin init failed: scale compiz (core) - Error: Failed to start plugin: scale compiz (core) - Info: Unloading plugin: scale Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Compiz (opengl) - Fatal: glXQueryExtensionsString is NULL for screen 0 Segmentation fault (core dumped)

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  • Listing both null and not null in mysql query

    - by tomasz
    Let's say I have the table NAME | ID | REF foo1 | 1 | NULL foo2 | 2 | 1234 foo2 | 3 | 567 foo1 | 4 | NULL foo3 | 5 | 89 I'd like to count all instances of NULL and NOT NULL in one query so that I can say NAME | null | not null foo1 | 0 | 2 foo2 | 2 | 0 foo3 | 0 | 1 I could run these two queries select NAME,count(*) from TABLE where REF is not null select NAME,count(*) from TABLE where REF is null But I'm sure there must be a simple way to do it in one mysql query.

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  • Null check error message as "is null" or "was null"

    - by Timo Westkämper
    When doing null checks in Java code, and you throw IllegalArgumentExceptions for null values, what kind of message template do you use? We tend to use something like this public User getUser(String username){ if (username == null){ throw new IllegalArgumentException("username is null"); } // ... } What is better : "is null" or "was null", and why? For me "is null" feels more natural.

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  • "Pointers" with $ Syntax in /etc/environment

    - by Tyson Trautmann
    Is it valid to have "pointers" in /etc/environment using $FOO syntax? Right now my /etc/environment looks like this: JAVA_HOME=/usr/lib/jvm/java-6-openjdk MAVEN_HOME=/usr/bin/apache-maven/apache-maven-3.0.4 M2_HOME=$MAVEN_HOME M2=$MAVEN_HOME/bin PATH=/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:$JAVA_HOME/bin:$MAVEN_HOME/bin I'm not getting the results that I'm expecting though: ~$ echo $JAVA_HOME /usr/lib/jvm/java-6-openjdk ~$ echo $MAVEN_HOME /usr/bin/apache-maven/apache-maven-3.0.4 ~$ echo $PATH /usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin/bin:/usr/games:$JAVA_HOME/bin:$MAVEN_HOME/bin

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  • pointers to functions

    - by DevAno1
    I have two basic Cpp tasks, but still I have problems with them. First is to write functions mul1,div1,sub1,sum1, taking ints as arguments and returning ints. Then I need to create pointers ptrFun1 and ptrFun2 to functions mul1 and sum1, and print results of using them. Problem starts with defining those pointers. I thought I was doing it right, but devcpp gives me errors in compilation. #include <iostream> using namespace std; int mul1(int a,int b) { return a * b; } int div1(int a,int b) { return a / b; } int sum1(int a,int b) { return a + b; } int sub1(int a,int b) { return a - b; } int main() { int a=1; int b=5; cout << mul1(a,b) << endl; cout << div1(a,b) << endl; cout << sum1(a,b) << endl; cout << sub1(a,b) << endl; int *funPtr1(int, int); int *funPtr2(int, int); funPtr1 = sum1; funPtr2 = mul1; cout << funPtr1(a,b) << endl; cout << funPtr2(a,b) << endl; system("PAUSE"); return 0; } 38 assignment of function int* funPtr1(int, int)' 38 cannot convertint ()(int, int)' to `int*()(int, int)' in assignment Task 2 is to create array of pointers to those functions named tabFunPtr. How to do that ?

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  • So which null equals this null, that null? maybe this null, or is it this null?

    - by GrumpyOldDBA
    Tuning takes many routes and I get into some interesting situations and often make some exciting finds, see http://sqlblogcasts.com/blogs/grumpyolddba/archive/2010/05/17/just-when-you-thought-it-was-safe.aspx for an example. Today I encountered a multitude of Foreign Key constraints on a table, now FKs are often candidates for indexes and as none of the defined keys had an index it required a closer look. I view foreign key constraints as somewhat of a pain, excessive keys can cause excessive related...(read more)

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  • Using pointers in PHP.

    - by Babiker
    I ask this question because i learned that in programming and designing, you must have a good reason for decisions. I am php learner and i am at a crossroad here, i am using simple incrementation to try to get what im askin across. I am certainly not here to start a debate about the pros/cons of pointers but when it comes to php, which is the better programming practice: function increment(&$param) { $param++; } Or function increment($param){ return $param++; } $param = increment($param);

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  • handling refrence to pointers/double pointers using SWIG [C++ to Java]

    - by Siddu
    My code has an interface like class IExample { ~IExample(); //pure virtual methods ...}; a class inheriting the interface like class CExample : public IExample { protected: CExample(); //implementation of pure virtual methods ... }; and a global function to create object of this class - createExample( IExample *& obj ) { obj = new CExample(); } ; Now, I am trying to get Java API wrapper using SWIG, the SWIG generated interface has a construcotr like - IExample(long cPtr, boolean cMemoryOwn) and global function becomes createExample(IExample obj ) The problem is when i do, IExample exObject = new IExample(LogFileLibraryJNI.new_plong(), true /*or false*/ ); createExample( exObject ); The createExample(...) API at C++ layer succesfully gets called, however, when call returns to Java layer, the cPtr (long) variable does not get updated. Ideally, this variable should contain address of CExample object. I read in documentation that typemaps can be used to handle output parameters and pointer references as well; however, I am not able to figure out the suitable way to use typemaps to resolve this problem, or any other workaround. Please suggest if i am doing something wrong, or how to use typemap in such situation?

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  • Check parameters annotated with @Nonnull for null?

    - by David Harkness
    We've begun using FindBugs with and annotating our parameters with @Nonnull appropriately, and it works great to point out bugs early in the cycle. So far we have continued checking these arguments for null using Guava's checkNotNull, but I would prefer to check for null only at the edges--places where the value can come in without having been checked for null, e.g., a SOAP request. // service layer accessible from outside public Person createPerson(@CheckForNull String name) { return new Person(Preconditions.checkNotNull(name)); } ... // internal constructor accessed only by the service layer public Person(@Nonnull String name) { this.name = Preconditions.checkNotNull(name); // remove this check? } I understand that @Nonnull does not block null values itself. However, given that FindBugs will point out anywhere a value is transferred from an unmarked field to one marked @Nonnull, can't we depend on it to catch these cases (which it does) without having to check these values for null everywhere they get passed around in the system? Am I naive to want to trust the tool and avoid these verbose checks? Bottom line: While it seems safe to remove the second null check below, is it bad practice? This question is perhaps too similar to Should one check for null if he does not expect null, but I'm asking specifically in relation to the @Nonnull annotation.

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  • MySql query optimization help

    - by rohitgu
    I have few queries and am not able to figure out how to optimize them, QUERY 1 select * from t_twitter_tracking where classified is null and tweetType='ENGLISH' order by id limit 500; QUERY 2 Select count(*) as cnt, DATE_FORMAT(CONVERT_TZ(wrdTrk.createdOnGMTDate,'+00:00','+05:30'),'%Y-%m-%d') as dat from t_twitter_tracking wrdTrk where wrdTrk.word like ('dell') and CONVERT_TZ(wrdTrk.createdOnGMTDate,'+00:00','+05:30') between '2010-12-12 00:00:00' and '2010-12-26 00:00:00' group by dat; Both these queries run on the same table, CREATE TABLE `t_twitter_tracking` ( `id` BIGINT(20) NOT NULL AUTO_INCREMENT, `word` VARCHAR(200) NOT NULL, `tweetId` BIGINT(100) NOT NULL, `twtText` VARCHAR(800) NULL DEFAULT NULL, `language` TEXT NULL, `links` TEXT NULL, `tweetType` VARCHAR(20) NULL DEFAULT NULL, `source` TEXT NULL, `sourceStripped` TEXT NULL, `isTruncated` VARCHAR(40) NULL DEFAULT NULL, `inReplyToStatusId` BIGINT(30) NULL DEFAULT NULL, `inReplyToUserId` INT(11) NULL DEFAULT NULL, `rtUsrProfilePicUrl` TEXT NULL, `isFavorited` VARCHAR(40) NULL DEFAULT NULL, `inReplyToScreenName` VARCHAR(40) NULL DEFAULT NULL, `latitude` BIGINT(100) NOT NULL, `longitude` BIGINT(100) NOT NULL, `retweetedStatus` VARCHAR(40) NULL DEFAULT NULL, `statusInReplyToStatusId` BIGINT(100) NOT NULL, `statusInReplyToUserId` BIGINT(100) NOT NULL, `statusFavorited` VARCHAR(40) NULL DEFAULT NULL, `statusInReplyToScreenName` TEXT NULL, `screenName` TEXT NULL, `profilePicUrl` TEXT NULL, `twitterId` BIGINT(100) NOT NULL, `name` TEXT NULL, `location` VARCHAR(100) NULL DEFAULT NULL, `bio` TEXT NULL, `url` TEXT NULL COLLATE 'latin1_swedish_ci', `utcOffset` INT(11) NULL DEFAULT NULL, `timeZone` VARCHAR(100) NULL DEFAULT NULL, `frenCnt` BIGINT(20) NULL DEFAULT '0', `createdAt` DATETIME NULL DEFAULT NULL, `createdOnGMT` VARCHAR(40) NULL DEFAULT NULL, `createdOnServerTime` DATETIME NULL DEFAULT NULL, `follCnt` BIGINT(20) NULL DEFAULT '0', `favCnt` BIGINT(20) NULL DEFAULT '0', `totStatusCnt` BIGINT(20) NULL DEFAULT NULL, `usrCrtDate` VARCHAR(200) NULL DEFAULT NULL, `humanSentiment` VARCHAR(30) NULL DEFAULT NULL, `replied` BIT(1) NULL DEFAULT NULL, `replyMsg` TEXT NULL, `classified` INT(32) NULL DEFAULT NULL, `createdOnGMTDate` DATETIME NULL DEFAULT NULL, `locationDetail` TEXT NULL, `geonameid` INT(11) NULL DEFAULT NULL, `country` VARCHAR(255) NULL DEFAULT NULL, `continent` CHAR(2) NULL DEFAULT NULL, `placeLongitude` FLOAT NULL DEFAULT NULL, `placeLatitude` FLOAT NULL DEFAULT NULL, PRIMARY KEY (`id`), INDEX `id` (`id`, `word`), INDEX `createdOnGMT_index` (`createdOnGMT`) USING BTREE, INDEX `word_index` (`word`) USING BTREE, INDEX `location_index` (`location`) USING BTREE, INDEX `classified_index` (`classified`) USING BTREE, INDEX `tweetType_index` (`tweetType`) USING BTREE, INDEX `getunclassified_index` (`classified`, `tweetType`) USING BTREE, INDEX `timeline_index` (`word`, `createdOnGMTDate`, `classified`) USING BTREE, INDEX `createdOnGMTDate_index` (`createdOnGMTDate`) USING BTREE, INDEX `locdetail_index` (`country`, `id`) USING BTREE, FULLTEXT INDEX `twtText_index` (`twtText`) ) COLLATE='utf8_general_ci' ENGINE=MyISAM ROW_FORMAT=DEFAULT AUTO_INCREMENT=12608048; The table has more than 10 million records. How can I optimize it?

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  • C++ simple arrays and pointers question

    - by nashmaniac
    So here's the confusion, let's say I declare an array of characters char name[3] = "Sam"; and then I declare another array but this time using pointers char * name = "Sam"; What's the difference between the two? I mean they work the same way in a program. Also how does the latter store the size of the stuff that someone puts in it, in this case 3 characters? Also how is it different from char * name = new char[3]; If those three are different where should they be used I mean in what circumstances?

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  • What's so bad about pointers in C++?

    - by Martin Beckett
    To continue the discussion in Why are pointers not recommended when coding with C++ Suppose you have a class that encapsulates objects which need some initialisation to be valid - like a network socket. // Blah manages some data and transmits it over a socket class socket; // forward declaration, so nice weak linkage. class blah { ... stuff TcpSocket *socket; } ~blah { // TcpSocket dtor handles disconnect delete socket; // or better, wrap it in a smart pointer } The ctor ensures that socket is marked NULL, then later in the code when I have the information to initialise the object. // initialising blah if ( !socket ) { // I know socket hasn't been created/connected // create it in a known initialised state and handle any errors // RAII is a good thing ! socket = new TcpSocket(ip,port); } // and when i actually need to use it if (socket) { // if socket exists then it must be connected and valid } This seems better than having the socket on the stack, having it created in some 'pending' state at program start and then having to continually check some isOK() or isConnected() function before every use. Additionally if TcpSocket ctor throws an exception it's a lot easier to handle at the point a Tcp connection is made rather than at program start. Obviously the socket is just an example, but I'm having a hard time thinking of when an encapsulated object with any sort of internal state shouldn't be created and initialised with new.

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  • PHP: why is this null different from the other null

    - by matthy
    hi i tried 2 things what should be the same however it my testing says different does anyone know why the only thing i do is put it in a variable... if ($_SESSION[$something] === null) echo("this is null"); $_SESSION[$something] does not exists so it indeed says: "this is null". now look at this $theSession = $_SESSION[$something]; if (theSession === null) echo("this is null"); now it does not say "this is null" while it should be exactly the same right?

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  • Difference between null==object and object==null

    - by priyank.mp
    Hi I would like to know diff between the above comparisons? I am getting null pointer exception when I check object.getItems() == null. But if I change it to null == object.getItems(), it workes fine. I did look into this http://stackoverflow.com/questions/2938476/what-is-the-difference-between-null-object-and-objectnull-closed But I didnt get satisfactory answer.

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  • "Null" is null or not an object error in IE javascript

    - by user89691
    The following code executes fine in Firefox and Chrome, but gives an error: 'null' is null or not an object when executed in Internet Explorer. if (xmlhttp.responseXML != null) { var xmlDoc = xmlhttp.responseXML.documentElement ; var ResultNodes = xmlDoc.getElementsByTagName ("Result") ; <---- error here if (ResultNodes != null) { (I would have thought the line after the one indicated would be more likely to return the error but the debugger says the run-time error is at the line indicated) Any ideas why?

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  • "Null" is null or not an object error in IE javascript

    - by rossmcm
    The following code executes fine in Firefox and Chrome, but gives an error: 'null' is null or not an object when executed in Internet Explorer. if (xmlhttp.responseXML != null) { var xmlDoc = xmlhttp.responseXML.documentElement ; var ResultNodes = xmlDoc.getElementsByTagName ("Result") ; <---- error here if (ResultNodes != null) { (I would have thought the line after the one indicated would be more likely to return the error but the debugger says the run-time error is at the line indicated) Any ideas why?

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  • NULL pointer comparison fails

    - by Ilya
    Hello, I'm initializing in a class a pointer to be NULL. Afterwards I check if it is NULL in the same class. But it's not always 0x0. Sometimes it's 0x8 or 0xfeffffff or 0x3f800000 or 0x80 or other strange stuff. In most case the pointer is 0x0 but sometimes it gets altered somehow. I'm sure that I'm not changing it anywhere in my code. Is there a way it gets changed by "itself"? Here's my code: MeshObject::MeshObject() { mesh.vertexColors = NULL; } MeshObject::MeshObject(const MeshObject &_copyFromMe) { SimpleLog("vertexColors pointer: %p", _copyFromMe.mesh.vertexColors); if (_copyFromMe.mesh.vertexColors != NULL) { SimpleLog("vertexColors"); this->mesh.vertexColors = new tColor4i[_copyFromMe.mesh.vertexCount]; memcpy(this->mesh.vertexColors, _copyFromMe.mesh.vertexColors, _copyFromMe.mesh.vertexCount * sizeof(tColor4i) ); } } My application crashes, because vertexColors wasn't initialized and is being copied. However it is NULL and shouldn't be copied. Thanks.

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