Search Results

Search found 10366 results on 415 pages for 'const char pointer'.

Page 315/415 | < Previous Page | 311 312 313 314 315 316 317 318 319 320 321 322  | Next Page >

• Best way to access nested data structures?

  - by Blackshark

  I would like to know what the best way (performance wise) to access a large data structure is. There are about hundred ways to do it but what is the most accessible for the compiler to optimize? One can access a value by foo[someindex].bar[indexlist[i].subelement[j]].baz[0] or create some pointer aliases like sometype_t* tmpfoo = &foo[someindex]; tmpfoo->bar[indexlist[i].subelement[j]].baz[0] or create reference aliases like sometype_t &tmpfoo = foo[someindex]; tmpfoo.bar[indexlist[i].subelement[j]].baz[0] and so forth...

  Read the article

• An array of structures in C...

  - by 00010000

  For the life of me I can't figure out the proper syntax for creating an array of structures in C. I tried this: struct foo { int x; int y; } foo[][] = { { { 1, 2 }, { 4, 5 }, { -1, -1 } }, { { 55, 44 } { 100, 200 }, } }; So for example foo[1][0].x == 100, foo[0][1].y == 5, etc. But GCC spits out a lot of errors. If anyone could provide the proper syntax that'd be great. EDIT: Okay, I tried this: struct foo { const char *x; int y; }; struct foo bar[2][] = { { { "A", 1 }, { "B", 2 }, { NULL, -1 }, }, { { "AA", 11 }, { "BB", 22 }, { NULL, -1 }, }, { { "ZZ", 11 }, { "YY", 22 }, { NULL, -1 }, }, { { "XX", 11 }, { "UU", 22 }, { NULL, -1 }, }, }; But GCC gives me "elements of array bar have incomplete type" and "excess elements in array initializer".

  Read the article

• How does make_pair know the types of its args?

  - by bobobobo

  The definition for make_pair in the MSVC++ "utility" header is: template<class _Ty1, class _Ty2> inline pair<_Ty1, _Ty2> make_pair(_Ty1 _Val1, _Ty2 _Val2) { // return pair composed from arguments return (pair<_Ty1, _Ty2>(_Val1, _Val2)); } I use make_pair all the time though without putting the argument types in angle brackets: map<string,int> theMap ; theMap.insert( make_pair( "string", 5 ) ) ; Shouldn't I have to tell make_pair that the first argument is std::string and not char* ? How does it know?

  Read the article

• CUDA Global Memory, Where is it?

  - by gamerx

  I understand that in CUDA's memory hierachy, we have things like shared memory, texture memory, constant memory, registers and of course the global memory which we allocate using cudaMalloc(). I've been searching through whatever documentations I can find but I have yet to come across any that explicitly explains what is the global memory. I believe that the global memory allocated is on the GDDR of graphics card itself and not the RAM that is shared with the CPU since one of the documentations did state that the pointer cannot be dereferenced by the host side. Am I right?

  Read the article

• Method to register method to be called when event is raised

  - by zaidwaqi

  I have a Panel which contains 20 PictureBox controls. If a user clicks on any of the controls, I want a method within the Panel to be called. How do I do this? public class MyPanel : Panel { public MyPanel() { for(int i = 0; i < 20; i++) { Controls.Add(new PictureBox()); } } // DOESN'T WORK. // function to register functions to be called if the pictureboxes are clicked. public void RegisterFunction( <function pointer> func ) { foreach ( Control c in Controls ) { c.Click += new EventHandler( func ); } } } How do I implement RegisterFunction()? Also, if there are cool C# features that can make the code more elegant, please share.

  Read the article

• Resolve circular typedef dependency?

  - by Nick

  What is the best way to resolve the following circular dependency in typedef-ing these structs? Note the C language tag - I'm looking for a solution in standard gcc C. typedef struct { char* name; int age; int lefthanded; People* friends; } Person; typedef struct { int count; int max; Person* data; } People;

  Read the article

• an error within context

  - by helloWorld

  can somebody please explain my mistake, I have this class: class Account{ private: string strLastName; string strFirstName; int nID; int nLines; double lastBill; public: Account(string firstName, string lastName, int id); friend string printAccount(string firstName, string lastName, int id, int lines, double lastBill); } but when I call it: string reportAccounts() const { string report(printAccountsHeader()); for(list<Account>::const_iterator i = listOfAccounts.begin(); i != listOfAccounts.end(); ++i){ report += printAccount(i->strFirstName, i->strLastName, i->nID, i->nLines, i->lastBill);; } return report; } I receive error within context, can somebody explain why? thanks in advance

  Read the article

• Make object by it's name

  - by Ockonal

  Hello, is it possible to return exemplar of object using passed type name (string) in c++? I have some base abstract class Base and a few derivates. Example code: class Base { /* ... */ }; class Der1 : public Base { /* ... */ }; class Der2 : public Base { /* ... */ }; And I need function like: Base *objectByType(const std::string &name); Number of derivates classes are changeable and I don't want to make something like switching of name and returning by hands new object type. Is it possible in c++ to do that automatically anyway? p.s. usage should looks like: dynamic_cast<Der1>(objectByType("Der1")); I need pure c++ code (crossplatform). Using boost is permissible.

  Read the article

• what's the meaning of ~0 in cpp or c

  - by rima

  Hi what's the meaning of ~0 in this code???? somebody can analysis this code for me? unsigned int Order(unsigned int maxPeriod = ~0) const { Point r = *this; unsigned int n = 0; while( r.x_ != 0 && r.y_ != 0 ) { ++n; r += *this; if ( n > maxPeriod ) break; } return n; } please help me soon....

  Read the article

• Layout of popup components changes while moving

  - by Le_Coeur

  I have designed some popup moving menu with JQuery, it looks perfekt in webkit browsers, but i have one problem in mozilla, when i move my popup window, layout of some components in this window changes! For example button add changes from: to: or to: , and it's absolutly random. What can it be? This image is in span: <span class="sw_link_add"></span> .sw_link_add { background:url("/img/confirm_new.png") no-repeat scroll right center transparent; cursor:pointer; padding-right:30px; padding-top:2px; }

  Read the article

• How can Java assignment be made to point to an object instead of making a copy?

  - by Matthew Piziak

  In a class, I have: private Foo bar; public Constructor(Foo bar) { this.bar = bar; } Instead of creating a copy of bar from the object provided in the parameter, is it possible to include a pointer to bar in the constructor such that changing the original bar changes the field in this object? Another way of putting it: int x = 7; int y = x; x = 9; System.out.print(y); //Prints 7. It is possible to set it up so that printing y prints 9 instead of 7?

  Read the article

• GWT : Composite not displaying

  - by animatrix30

  I have a this code for the layout : grid = new Grid(15, 15); tiles = new Tile[15][15]; for (int i = 0; i != 15; i++) { for (int j = 0; j != 15; j++) { tiles[i][j] = new Tile('a'); grid.setWidget(i, j, tiles[i][j]); tiles[i][j].setVisible(true); } } initWidget(grid); I know it is working, because if I change the tile, by a Button, it works well. Now my Tile class : public class Tile extends Composite { char character; public Tile (Character c) { this.character = c; buildWidget(); } private void buildWidget() { Label l = new Label(this.character+""); initWidget(l); } Why does all tiles are not displayed ? Thanks for your help !

  Read the article

• How does the stream manipulators work?

  - by Narek

  It is well known that the user can define stream manipulators like this: ostream& tab(ostream & output) { return output<< '\t'; } And this can be used in main() like this: cout<<'a'<<tab<<'b'<<'c'<<endl; Please explain me how does this all work? If operator<< assumes as a second parameter a pointer to the function that takes and returns ostream &, then please explain my why it is necessary? What would be wrong if the function does not take and return ostream & but it was void instead of ostream &? Also it is interesting why “dec”, “hex” manipulators take effect until I don’t change between them, but user defined manipulators should be always used in order to take effect for each streaming?

  Read the article

• Button border radius and cursor

  - by noober

  CSS border radius does affect button rendering (I see it's round form), but does not affect how it interacts with the user (I still can click button outside its border). How should I fix it? I see the behavior in Chrome. button { cursor: pointer; outline: none; background-size: 100% 100%; background-color: red; /*transparent;*/ /* It's actually red and ROUND. */ background-position: center center; background-repeat: no-repeat; border: 0px; -webkit-border-top-left-radius: 73px; -webkit-border-top-right-radius: 73px; -webkit-border-bottom-left-radius: 73px; -webkit-border-bottom-right-radius: 73px; width: 146px; height: 146px; background-image: url('leftarrow.png'); } Regards,

  Read the article

• creating new array according to input

  - by gcc

  int *arrays[20],j,a=0; /*int num_arrays;*/ char *tutar[200]; int /*fe*/i=0,n,temp; do{ tutar[i]=malloc(sizeof(int)); scanf("%s",tutar[i]); temp=*tutar[i]; ++i; } while(temp!='x'); int *arrays[20],j,a=0; n=i; j=1; for(i=1;i if(atoi(tutar[i])=='n') { ++j; arrays[j]=malloc(sizeof(int)); a=0; } arrays[j][a]=*(int *)tutar[i]; if(atoi(tutar[i])=='x') break; } input: 1 2 3 4 n 14 23 39 n 98 100 x output: arrays[1]:2 3 4 arrays[2]:14 23 39 arrays[3]:98 100 //i wanna output like that but my code didnt give me output like that //can anyone fix my code or (explain where is my error)

  Read the article

• Is there a method to retrieve the file name of a class?

  - by Dran Dane

  Hello Is there a method to retrieve the file name of a class? Specifically I would like to create a static method (CreateLink) in a base class (BasePage) to automatically return the path and filename of the page called. I code in .C# ASP.NET private const string TEMPLATE = "~/One.aspx"; public static HyperLink CreateLink() { HyperLink link = new HyperLink(); link.Text = "Click here"; link.NavigateUrl = String.Format(TEMPLATE); return link; } Is it possible to avoid the use of TEMPLATE hardcoded variable? Is it possible to retrieve the One.aspx path from file name and location?

  Read the article

• What types of conditions can be used for conditional compilation in C++?

  - by user1002288

  This is an exam question for C++: Which of the following statements accurately describe the condition that can be used for conditional compilation in C++? A. The condition can depend on the value of environment variables. B. The condition can depend on the value of any const variables. C. The condition can depend on the value of program variables. D. The condition can use the sizeof() operator to make decision about compiler-dependent operations based on the size of standard data type. E. The condition must evaluate to either a 0 or 1 during preprocessing. I think the answer is E. Is this correct?

  Read the article

• Are unspecified and undefined behavior required to be consistent between compiles?

  - by sharptooth

  Let's pretend my program contains a specific construct the C++ Standard states to be unspecified behavior. This basically means the implementation has to do something reasonable but is allowed not to document it. But is the implementation required to produce the same behavior every time it compiles a specific construct with unspecified behavior or is it allowed to produce different behavior in different compiles? What about undefined behavior? Let's pretend my program contains a construct that is UB according to the Standard. The implementation is allowed to exhibit any behavior. But can this behavior differ between compiles of the same program on the same compiler with same settings in the same environment? In other words, if I dereference a null pointer on line 78 in file X.cpp and the implementation formats the drive in such case does it mean that it will do the same after the program is recompiled?

  Read the article

• How to get path to current exe file on Linux?

  - by user1519221

  The code below gives current path to exe file on Linux: #include <iostream> std::string getExePath() { char result[ PATH_MAX ]; ssize_t count = readlink( "/proc/self/exe", result, PATH_MAX ); return std::string( result, (count > 0) ? count : 0 ); } int main() { std::cout << getExePath() << std::endl; return 0; } The problem is that when I run it gives me current path to exe and name of the exe, e.g.: /home/.../Test/main.exe I would like to get only /home/.../Test/ I know that I can parse it, but is there any nicer way to do that?

  Read the article

• Memory allocated with malloc does not persist outside function scope?

  - by PM

  Hi, I'm a bit new to C's malloc function, but from what I know it should store the value in the heap, so you can reference it with a pointer from outside the original scope. I created a test program that is supposed to do this but I keep getting the value 0, after running the program. What am I doing wrong? int f1(int * b) { b = malloc(sizeof(int)); *b = 5; } int main() { int * a; f1(a); printf("%d\n", a); return 0; }

  Read the article

• Help with implementing a function to change size of dynamic array

  - by iRobot

  I'm trying to write a function that will change the size of a dynamic array to a new size. In my header file, I have: Image **images; //pointer to a dynamic array of image pointers int maximum; //size I want to do this by allocating a new array and copying the values over without changing their indices. If there are non-null pointers outside the range newmax, then we cant do this. So heres what I have: There are no compilation or runtime errors. However, I find that the new array isnt getting sized right. When I run the following test case: I should get an index out of bounds error, but instead the system lets it slide. Can anyone see the mistake? I've looked for hours but cant find anything.

  Read the article

• Regex: Match opening/closing chars with spaces

  - by Israfel

  I'm trying to complete a regular expression that will pull out matches based on their opening and closing characters, the closest I've gotten is ^(\[\[)[a-zA-Z.-_]+(\]\]) Which will match a string such as "[[word1]]" and bring me back all the matches if there is more than one, The problem is I want it to pick up matchs where there may be a space in so for example "[[word1 word2]]", now this will work if I add a space into my pattern above however this pops up a problem that it will only get one match for my entire string so for example if I have a string "Hi [[Title]] [[Name]] [[surname]], How are you" then the match will be "[[Title]] [[Name]] [[surname]]" rather than 3 matches "[[Title]]", "[[Name]]", "[[surname]]". I'm sure I'm just a char or two away in the Regex but I'm stuck, How can I make it return the 3 matches. Thanks

  Read the article

• .NET Regex - need matching string for parsing...

  - by TomTom

  Hello, I am a regex idiot and never found a good tutorial (links welcome, as well as a pointer to an interactive VS2010 integrated editor). I need to parse strings in the following form: [a/b]:c/d a, b: double with "." as possible separator. CAN be empty c: double with "." as separator d: integer, positive I.e. valid strings are: [/]:0.25/2 [-0.5/0.5]:0.05/2 [/0.1]:0.05/2 ;) Anyone can help? Thanks

  Read the article

• How to algorithmically partion a keyspace?

  - by pbhogan

  This is related to consistent hashing and while I conceptually understand what I need to do, I'm having a hard time translating this into code. I'm trying to divide a given keyspace (say, 128 bits) into equal sized partitions. I want the upper bound (highest key) of each partition. Basically, how would I complete this? #define KEYSPACE_BYTE_SIZE 16 #define KEYSPACE_BIT_SIZE (KEYSPACE_BYTE_SIZE * 8) typedef struct _key { char byte[KEYSPACE_BYTE_SIZE]; } key; key * partition_keyspace( int num_partitions ) { key * partitions = malloc( sizeof(key) * num_partitions ); // ... }

  Read the article

• Why does a non-constant offsetof expression work?

  - by Chris J. Kiick

  Why does this work: #include <sys/types.h> #include <stdio.h> #include <stddef.h> typedef struct x { int a; int b[128]; } x_t; int function(int i) { size_t a; a = offsetof(x_t, b[i]); return a; } int main(int argc, char **argv) { printf("%d\n", function(atoi(argv[1]))); } If I remember the definition of offsetof correctly, it's a compile time construct. Using 'i' as the array index results in a non-constant expression. I don't understand how the compiler can evaluate the expression at compile time. Why isn't this flagged as an error?

  Read the article

< Previous Page | 311 312 313 314 315 316 317 318 319 320 321 322  | Next Page >