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  • Initializing an array after declaration

    - by robUK
    Hello, gcc 4.4.3 c89 I have the following code as a sample of what I am trying to do. I don't know the actual size of the array, until I enter the function. However, I don't think I can set the array size after I have declared it. I need it global as some other functions will need to access the device names. Many thanks for any suggestions, /* global */ char *devices_names[]; void fill_devices(size_t num_devices) { devices_names[num_devices]; /* start filling */ }

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  • [C++] Simple inheritance question

    - by xbonez
    I was going over some sample questions for an upcoming test, and this question is totally confusing me. Any help would be appreciated. Consider the following code: class GraduateStudent : public Student { ... }; If the word "public" is omitted, GraduateStudent uses private inheritance, which means which of the following? GraduateStudent objects may not use methods of Student. GraduateStudent does not have access to private objects of Student. No method of GraduateStudent may call a method of Student. Only const methods of GraduateStudent can call methods of Student.

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  • 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".

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  • how to specify a pointer to an overloaded function?

    - by davka
    I want to pass an overloaded function to the std::for_each() algorithm. e.g.: void f(char c); void f(int i); std::string s("example"); std::for_each(s.begin(), s.end(), f); I'd expect the compiler to resolve f() by the iterator type. Apparently, it (gcc 4.1.2) doesn't do it. So, how can I specify which f() I want? thanks a lot

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  • Why does the Win32-API have so many custom types?

    - by sub
    I'm new to the Win32 API and the many new types begin to confuse me. Some functions take 1-2 ints and 3 UINTS as arguments. Why can't they just use ints? What are UINTS? Then, there are those other types: DWORD LPCWSTR LPBOOL Again, I think the "primitive" C types would be enough - why introduce 100 new types? This one was a pain: WCHAR* I had to iterate through it and push_back every character to an std::string as there wasn't another way to convert it to one. Horrible. Why WCHAR? Why reinvent the wheel? They could have just used char* instead, or?

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  • C++: Delete a struct?

    - by Rosarch
    I have a struct that contains pointers: struct foo { char* f; int* d; wchar* m; } I have a vector of shared pointers to these structs: vector<shared_ptr<foo>> vec; vec is allocated on the stack. When it passes out of scope at the end of the method, its destructor will be called. (Right?) That will in turn call the destructor of each element in the vector. (Right?) Does calling delete foo delete just the pointers such as foo.f, or does it actually free the memory from the heap?

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  • xcode 4 creating a 2d grid (range and domain)

    - by user1706978
    I'm learning how to program c and i'm trying to make a program the finds the range (using an equation with x as the domain) of a 2d grid...ive already attempted it, but it's giving me all these errors on Xcode, any help?(As you can see, I'm quite stuck!) #include <stdio.h> #include <stdlib.h> float domain; float domain = 2.0; float domainsol(float x ) { domain = x; float func = 1.25 * x + 5.0; return func; } int main(int argc, const char * argv[]) { }

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  • Writing different structs to a file in C++? [on hold]

    - by user58053
    I need a way to write structures of three different kinds to a binary file, which later has to be searched. (As in, for example, struct A has two fields, an int and a char; struct B has int and a long; I need to output all structures whose int equals the one given from keyboard). I understand how to write structs of the same kind to a file and how to search them, but here I am just lost, best thing I came up with is declaring a struct containing all possibly needed fields and leaving the ones I don't need empty, but it really feels wrong, there HAS to be a better way to do that. I've read about binary files and could not find anything relevant, most examples and tutorials deal with writing one data type. Could anyone point me in the right direction? EDIT: I am looking for what @Jerry_coffin called database mode, and will probably use one of the existing database systems for that, best way to go, probably. Thank you everybody for the suggestions

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  • [VC++ 2010] Stack around the variable 'xyz' was corrupted.

    - by tirolerhut
    hi, I'm trying to get some simple piece of code I found on a website to work in VC++ 2010 on windows vista 64: #include "stdafx.h" #include <windows.h> int _tmain(int argc, _TCHAR* argv[]) { DWORD dResult; BOOL result; char oldWallPaper[MAX_PATH]; result = SystemParametersInfo(SPI_GETDESKWALLPAPER, sizeof(oldWallPaper)-1, oldWallPaper, 0); fprintf(stderr, "Current desktop background is %s\n", oldWallPaper); return 0; } it does compile, but when I run it, I always get this error: Run-Time Check Failure #2 - Stack around the variable 'oldWallPaper' was corrupted. I'm not sure what is going wrong, but I noticed, that the value of oldWallPaper looks something like "C\0\:\0\0U\0s\0e\0r\0s[...]" -- I'm wondering where all the \0s come from. A friend of mine compiled it on windows xp 32 (also VC++ 2010) and is able to run it without problems any clues/hints/opinions? thanks

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  • Read text and print each (byte) character in separate line

    - by user2967663
    preforming this code to read file and print each character \ (byte) in separate line works well with ASCII void preprocess_file (FILE *fp) { int cc; for (;;) { cc = getc (fp); if (cc == EOF) break; printf ("%c\n", cc); } } int main(int argc, char *argv []) { preprocess_file (stdin); exit (0); } but when i use it with UTF-8 encoded text it shows unredable character such as ï » ? ? § ? „ ? … ? ¤ ? ´ ? and advice ? Thanks

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  • 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?

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  • Obtain container type from (its) iterator type in C++ (STL)

    - by KRao
    It is easy given a container to get the associated iterators, example: std::vector<double>::iterator i; //An iterator to a std::vector<double> I was wondering if it is possible, given an iterator type, to deduce the type of the "corresponding container" (here I am assuming that for each container there is one and only one (non-const) iterator). More precisely, I would like a template metafunction that works with all STL containers (without having to specialize it manually for each single container) such that, for example: ContainerOf< std::vector<double>::iterator >::type evaluates to std::vector<double> Is it possible? If not, why? Thank you in advance for any help!

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  • 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 !

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  • 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)

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  • 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

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  • 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?

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  • CString a = "Hello " + "World!"; Is it possible?

    - by Sanctus2099
    I'm making my own string class and I was wondering if there's any way to replace the compiler behaviour around " characters. As I said in the title I'd like to make it so that CString a = "Hello " + "World!"; would actually work and not give a compiler error telling that it can't add 2 pointers. My string class automatically converts to char* when needed and thus writing printf(a) would not break the code. I'm sure this is a rather weird question but if it's possible I'd really like to know how to do it. Thank you very much

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  • Sending some byte at time

    - by user1417815
    I'm trying to figure out way to send some amount of text from the string ech time until it reach the end of the string, example: const char* the_string = "hello world, i'm happy to meet you all. Let be friends or maybe more, but nothing less" Output: hello world Output: , i'm happy to meet you all. Output: Let be friends or maybe more Output: , but nothing less stop: no more bytes to send. the problem i have searched google, but didn't understand the examples, i spent 4 days trying find a good way, also that sendt 5 bytes at time, but in case there is less, then send them until you are at the end of the string. please help me out guys, i will accept a C or C++ way, as long it works and well explained.

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  • 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

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  • Pointer aliasing- in C++0x

    - by DeadMG
    I'm thinking about (just as an idea) disjointed pointer aliasing in C++0x. I was thinking about seeing if it could be implemented similarly to const correctness- that is, enforced by the compiler. What would be the requirements for such a thing? As this is more of a thought experiment, I'm perfectly happy to look at solutions that destroy legacy code or redefine half the language and that kind of thing. What I'd really rather not do is have, say, restrict from C99 where the programmer just promises it. It should be enforced.

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  • You have an error in your SQL syntax; check the manual that corresponds to your MySQL

    - by LuisEValencia
    I am trying to run a mysql query to find all occurences of a text. I have a syntax error but dont know where or how to fix it I am using sqlyog to execute this script DECLARE @url VARCHAR(255) SET @url = '1720' SELECT 'select * from ' + RTRIM(tbl.name) + ' where ' + RTRIM(col.name) + ' like %' + RTRIM(@url) + '%' FROM sysobjects tbl INNER JOIN syscolumns col ON tbl.id = col.id AND col.xtype IN (167, 175, 231, 239) -- (n)char and (n)varchar, there may be others to include AND col.length > 30 -- arbitrary min length into which you might store a URL WHERE tbl.type = 'U' -- user defined table 1 queries executed, 0 success, 1 errors, 0 warnings Query: declare @url varchar(255) set @url = '1720' select 'select * from ' + rtrim(tbl.name) + ' where ' + rtrim(col.name) + ' like %' ... Error Code: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'declare @url varchar(255)

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  • Mapping C structure to an XML element

    - by EFraim
    Suppose I have a structure in C or C++, such as: struct ConfigurableElement { int ID; char* strName; long prop1; long prop2; ... }; I would like to load/save it to/from the following XML element: <ConfigurableElement ID="1" strName="namedElem" prop1="2" prop2="3" ... /> Such a mapping can be trivially done in Java/C# or any other language with run-time reflection for the matter. Can it be done in any non-tedious way in C++ with macros/template trickery? Bonus points for handling nested structures/unions.

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  • How to copy a structure with pointers to data inside (so to copy pointers and data they point to)?

    - by Kabumbus
    so I have a structure like struct GetResultStructure { int length; char* ptr; }; I need a way to make a full copy of it meaning I need a copy to have a structure with new ptr poinnting on to copy of data I had in original structure. Is It any how possible? I mean any structure I have which contains ptrs will have some fields with its lengths I need a function that would copy my structure coping all ptrs and data they point to by given array of lengthes... Any cool boost function for it? Or any way how to create such function?

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  • In a C++ template, is it allowed to return an object with specific type parameters?

    - by nieldw
    When I've got a template with certain type parameters, is it allowed for a function to return an object of this same template, but with different types? In other words, is the following allowed? template<class edgeDecor, class vertexDecor, bool dir> Graph<edgeDecor,int,dir> Graph<edgeDecor,vertexDecor,dir>::Dijkstra(vertex s, bool print = false) const { /* Construct new Graph with apropriate decorators */ Graph<edgeDecor,int,dir> span = new Graph<edgeDecor,int,dir>(); /* ... */ return span; }; If this is not allowed, how can I accomplish the same kind of thing?

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