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  • some qeustions about Vector in STL

    - by skydoor
    I have some questions about vector in STL to clarify..... 1 Where are the objects in vector allocated? heap? 2 does vector have boundary check? If the index out of the boundary, what error will happen? 3 Why array is faster than vector? 4 Is there any case in which vector is not applicable but array is a must?

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  • How to use length indicator in a C++ program

    - by cj
    I want to make a program in C++ that reads a file where each field will have a number before it that indicates how long it is. The problem is I read every record in object of a class; how do I make the attributes of the class dynamic? For example if the field is "john" it will read it in a 4 char array. I don't want to make an array of 1000 elements as minimum memory usage is very important.

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  • Math.min.apply(0, x) - why?

    - by Trevor Burnham
    I was just digging through some JavaScript code (Raphaël.js) and came across the following line (translated slightly): Math.min.apply(0, x) where x is an array. Why on earth would you do this? The behavior seems to be "take the min from the array x."

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  • is there a proper way to handle multiple errors/exceptions?

    - by toPeerOrNotToPeer
    in OO programming, is there some conceptual pattern, ideas, about handling multiple errors? for example, i have a method that performs some checks and should return an error message for each error found ['name is too short', 'name contains invalid unicode sequences', 'name is too long'] now, should i use an array of exceptions (not thrown exceptions)? or something like this is better: class MyExceptionList extends Exception{ public Void addException(Exception e){} public Array getExceptions(){} } any theory behind this argument will be appreciated! (this isn't a request about a specific programming language, but a pure theoretical one) thank you in advance

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  • What is an alternative for split in Perl?

    - by joe
    My file contains a: b d: e f: a:b:c g: a b c d f:g:h h: d d:dd:d J: g,j How can I parse this file into lefthand side values into one array and right hand side to another array? I tried with split, but I am not able to get it back. I want to store them into hash.

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  • java dynamic function calling

    - by dpaksp
    here is that case....i have an String array that contains only method names of yyyyyy.java file in xxxxxx.java file am creaing yyyyyy.java 's instance (say obj) now i have access obj.fuction_name....that function i should get from that String array in loop ...is that possible ... thank u

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  • 2d convolution using python and numpy

    - by mikip
    Hi I am trying to perform a 2d convolution in python using numpy I have a 2d array as follows with kernel H_r for the rows and H_c for the columns data = np.zeros((nr, nc), dtype=np.float32) #fill array with some data here then convolve for r in range(nr): data[r,:] = np.convolve(data[r,:], H_r, 'same') for c in range(nc): data[:,c] = np.convolve(data[:,c], H_c, 'same') It does not produce the output that I was expecting, does this code look OK Thanks

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  • Can I use the [] operator in C++ to create virtual arrays

    - by Shane MacLaughlin
    I have a large code base, originally C ported to C++ many years ago, that is operating on a number of large arrays of spatial data. These arrays contain structs representing point and triangle entities that represent surface models. I need to refactor the code such that the specific way these entities are stored internally varies for specific scenarios. For example if the points lie on a regular flat grid, I don't need to store the X and Y coordinates, as they can be calculated on the fly, as can the triangles. Similarly, I want to take advantage of out of core tools such as STXXL for storage. The simplest way of doing this is replacing array access with put and get type functions, e.g. point[i].x = XV; becomes Point p = GetPoint(i); p.x = XV; PutPoint(i,p); As you can imagine, this is a very tedious refactor on a large code base, prone to all sorts of errors en route. What I'd like to do is write a class that mimics the array by overloading the [] operator. As the arrays already live on the heap, and move around with reallocs, the code already assumes that references into the array such as point *p = point + i; may not be used. Is this class feasible to write? For example writing the methods below in terms of the [] operator; void MyClass::PutPoint(int Index, Point p) { if (m_StorageStrategy == RegularGrid) { int xoffs,yoffs; ComputeGridFromIndex(Index,xoffs,yoffs); StoreGridPoint(xoffs,yoffs,p.z); } else m_PointArray[Index] = p; } } Point MyClass::GetPoint(int Index) { if (m_StorageStrategy == RegularGrid) { int xoffs,yoffs; ComputeGridFromIndex(Index,xoffs,yoffs); return GetGridPoint(xoffs,yoffs); // GetGridPoint returns Point } else return m_PointArray[Index]; } } My concern is that all the array classes I've seen tend to pass by reference, whereas I think I'll have to pass structs by value. I think it should work put other than performance, can anyone see any major pitfalls with this approach. n.b. the reason I have to pass by value is to get point[a].z = point[b].z + point[c].z to work correctly where the underlying storage type varies.

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  • Zend_Filter_StripTags ignoring allowed tags and attributes

    - by Jhorra
    I'm trying to use the following code and it still strips out all the tags. Am I doing something wrong? I'm using the newest V1.10 $allowed_tags = array('img', 'object', 'param', 'embed', 'a', 'href', 'p', 'br', 'em', 'strong', 'li', 'ol', 'span'); $allowed_attributes = array('style', 'src', 'alt', 'href', 'width', 'height', 'value', 'name', 'type', 'embed', 'quality', 'pluginspage'); Zend_Loader::loadClass('Zend_Filter_StripTags'); $html_filter = new Zend_Filter_StripTags($allowed_tags, $allowed_attributes); $post = $html_filter->filter($this->_request->getPost('post'));

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  • Request for member Name in something not a structure or Union

    - by Ashutosh
    Hey Folks, I am trying to Call the webservices in my app and while checking it in console it's showing the number of objects. (as i am using the Mutable array) and then while trying to display the name of the objects (here it's location) it's giving me an error in this line for (SDZArrayOfLocationWithLatestGrades* location in a) { NSLog(@" - %@", location.Name); // error here and a is the mutable array } PLease help me with this and Happy New Year to All!!!!!! Thanks,

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  • Extend multiple classes at once

    - by Starkers
    I want to share a method amongst all Ruby's data object classes. That is to say the following classes: Hash String Number Array Firstly, any classes I've missed out? Secondly, how can I share my_method amongst all classes at once? class Hash def my_method "hi" end end class String def my_method "hi" end end class Number def my_method "hi" end end class Array def my_method "hi" end end

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  • NSMutableDictionary confused over how to use keys with certain code ?

    - by Jules
    I'm getting data from a database and I need to add the string field value and the record id. However, I need this to work with some existing code... I'm replacing this (see code below) and getting data from my database. NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfFile:path]; self.allCategories = dict; [dict release]; But needs to work with these key and value search functions. - (void)resetSearch { NSMutableDictionary *allCategoriesCopy = [self.allCategories mutableDeepCopy]; self.Categories = allCategoriesCopy; [allCategoriesCopy release]; NSMutableArray *keyArray = [[NSMutableArray alloc] init]; [keyArray addObject:UITableViewIndexSearch]; [keyArray addObjectsFromArray:[[self.allCategories allKeys] sortedArrayUsingSelector:@selector(compare:)]]; self.keys = keyArray; [keyArray release]; } . - (void)handleSearchForTerm:(NSString *)searchTerm { NSMutableArray *sectionsToRemove = [[NSMutableArray alloc] init]; [self resetSearch]; for (NSString *key in self.keys) { NSMutableArray *array = [Categories valueForKey:key]; NSMutableArray *toRemove = [[NSMutableArray alloc] init]; for (NSString *name in array) { if ([name rangeOfString:searchTerm options:NSCaseInsensitiveSearch].location == NSNotFound) [toRemove addObject:name]; } if ([array count] == [toRemove count]) [sectionsToRemove addObject:key]; [array removeObjectsInArray:toRemove]; [toRemove release]; } [self.keys removeObjectsInArray:sectionsToRemove]; [sectionsToRemove release]; [table reloadData]; } Keep getting an error from this code... NSDictionary *arrayTmp= [[NSDictionary alloc] init]; ... loop records int cid = sqlite3_column_int(statementTMP, 0); NSString *category = [[NSString alloc] initWithUTF8String:(char *)sqlite3_column_text(statementTMP, 1)]; [arrayTmp setObject:category forKey:[NSString stringWithFormat:@"%i", cid]]; Error caused by line above * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSCFString count]: unrecognized selector sent to instance 0x4d4c500' * Call stack at first throw * ... end loop self.allCategories = arrayTmp; [arrayTmp release];

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  • string s; &s+1; Legal? UB?

    - by John Dibling
    Consider the following code: #include <cstdlib> #include <iostream> #include <string> #include <vector> #include <algorithm> using namespace std; int main() { string myAry[] = { "Mary", "had", "a", "Little", "Lamb" }; const size_t numStrs = sizeof(myStr)/sizeof(myAry[0]); vector<string> myVec(&myAry[0], &myAry[numStrs]); copy( myVec.begin(), myVec.end(), ostream_iterator<string>(cout, " ")); return 0; } Of interest here is &myAry[numStrs]: numStrs is equal to 5, so &myAry[numStrs] points to something that doesn't exist; the sixth element in the array. There is another example of this in the above code: myVec.end(), which points to one-past-the-end of the vector myVec. It's perfecly legal to take the address of this element that doesn't exist. We know the size of string, so we know where the address of the 6th element of a C-style array of strings must point to. So long as we only evaluate this pointer and never dereference it, we're fine. We can even compare it to other pointers for equality. The STL does this all the time in algorithms that act on a range of iterators. The end() iterator points past the end, and the loops keep looping while a counter != end(). So now consider this: #include <cstdlib> #include <iostream> #include <string> #include <vector> #include <algorithm> using namespace std; int main() { string myStr = "Mary"; string* myPtr = &myStr; vector<string> myVec2(myPtr, &myPtr[1]); copy( myVec2.begin(), myVec2.end(), ostream_iterator<string>(cout, " ")); return 0; } Is this code legal and well-defined? It is legal and well-defined to take the address of an array element past the end, as in &myAry[numStrs], so should it be legal and well-defined to pretend that myPtr is also an array?

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  • Thread safety in C# arrays

    - by Betamoo
    Does having 2 different threads : one reading from a C# array (e.g from first location), and another one writing to the same C# array but to a different location(e.g to the last location) is thread safe or not? (And I mean here without locking reading nor writing)

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  • Facebook API, export group wall entries

    - by Guy David
    After trying to find a reference to an API/tutorial to such thing, I have come here. I would like to scan a specific group wall, pulling all posts from it, with PHP or C#. In the end, I would like to have a nested-array containing each posts, with the next details: An array of the related comments Likes Views Obviously, I don't ask for any code, only a reference to the related API I will need to use. EDIT: If this is not possible, should I consider cURL as an option?

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  • Why doesn't Java allow for the creaton of generic arrays?

    - by byte
    There are plenty of questions on stackoverflow from people who have attempted to create an array of generics like so: ArrayList<Foo>[] poo = new ArrayList<Foo>[5]; And the answer of course is that the Java specification doesn't allow you to declare an array of generics. My question however is why ? What is the technical reason underlying this restriction in the java language or java vm? It's a technical curiosity I've always wondered about.

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  • Need Help Loading and Manipulating Bitmap Data

    - by Dave
    Using VB6, I need to load a bitmap image and subsequently manipulate some of its data - specifically, I want to rotate a section within the image, and in the end keep the image intact with the rotated section. How do I (1) find out where an image gets loaded into memory (a physical address), and (2) in what format is it stored, a 1-D array, 2-D array, or what? Maybe you can even suggest a better way to do this. Thanks.

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  • Python | How to send a JSON response with name assign to it

    - by MMRUser
    How can I return an response (lets say an array) to the client with a name assign to it form a python script. echo '{"jsonValidateReturn":'.json_encode($arrayToJs).'}'; in this scenario it returns an array with the name(jsonValidateReturn) assign to it also this can be accessed by jsonValidateReturn[1],so I want to do the same using a python script. I tried it once but it didn't go well array_to_js = [vld_id, vld_error, False] array_to_js[2] = False jsonValidateReturn = simplejson.dumps(array_to_js) return HttpResponse(jsonValidateReturn, mimetype='application/json') Thanks.

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  • Correct use of a "for...in" loop in javascript?

    - by jnkrois
    Hello everybody, before I ask my question I wanted to let everybody know that I appreciate the fact that there's always somebody out there willing to help, and on my end I'll try to give back to the community as much as I can. Thanks Now, I would like to get some pointers as to how to properly take advantage of the "for...in" loop in JavaScript, I already did some research and tried a couple things but it is still not clear to me how to properly use it. Let's say I have a random number of "select" tags in an HTML form, and I don't require the user to select an option for all of them, they can leave some untouched if they want. However I need to know if they selected none or at least one. The way I'm trying to find out if the user selected any of them is by using the "for...in" loop. For example: var allSelected = $("select option:selected"); var totalSelected = $("select option:selected").length; The first variable produces an array of all the selected options. The second variable tells me how many selected options I have in the form (select tags could be more than one and it changes every time). Now, in order to see if any has been selected I loop through each element (selected option), and retrieve the "value" attribute. The default "option" tag has a value="0", so if any selected option returns a value greater than 0, I know at least one option has been selected, however it does not have to be in order, this is my loop so far: for(var i = 0; i < totalSelected; i++){ var eachOption = $(allSelected[i]).val(); var defaultValue = 0; if(eachOption == defaultValue){ ...redirect to another page }else if(eachOption > defaultValue){ ... I display an alert } } My problem here is that as soon as the "if" matches a 0 value, it sends the user to the next page without testing the rest of the elements in the array, and the user could have selected the second or third options. What I really want to do is check all the elements in the array and then take the next action, in my mind this is how I could do it, but I'm not getting it right: var randomValue = 25; for(randomValue in allSelected){ var found = true; var notFound = false if(found){ display an alert }else{ redirect to next page } } This loop or the logic I'm using are flawed (I'm pretty sure), what I want to do is test all the elements in the array against a single variable and take the next action accordingly. I hope this makes some sense to you guys, any help would be appreciated. Thanks, JC

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  • php mysql_query return empty value

    - by proyb2
    I create a directory listing and came across this issue. what value does mysql_query($query1) return if there is no value My script received this message from $result, would it be alright to pass array(0)? Warning: mysql_fetch_array($result) expects parameter 1 to be resource, array given in

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  • Retaining objects in game iphone

    - by Brodie4598
    Hello - I am trying to create a game and have run into what is probably a pretty easy problem to solve. As the player goes through the game, many objects (Vehicle) will be added and removed. The Vehicles get added to an array called currentVehiclesMutableArray. My problem is I cant figure out how to retain a Vehicle so that it remains in the array until I am finished with it.

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