pointers

Initializing array of pointers to char

When I try to compile the following code I receive an error: "Type error in argument 1 to 'allocate'; found 'char * *', expected 'char *" at the line indicated (<<<<<). Explanations would be appreciated. #include <stdio.h> #include <string.h> void allocate(char *dt); int main(void) { char *data[3]; allocate(data); <<<<< retu...

Increasing a pointer not compiling the way I had planned

Hello, I tried to make my code as simple as possible,but I failed at it. This is my code: class function TWS.WinsockSend(s:integer;buffer:pointer;size:word):boolean; begin dwError := Send(s,buffer,size,0); // Debug if(dwError = SOCKET_ERROR) then begin dwError := WSAGetLastError; CloseSocket(s); WSACleanup; case ...

C Formatting Question (%d versus %u)

What is difference between %d and %u when printing pointer addresses? For example: int a=5; // check the memory address printf("memory add=%d\n", &a); // prints "memory add=-12" printf("memory add=%u\n", &a); // prints "memory add=65456" Please define. ...

Double pointer doubts in C

I have written a program in which in the main function I declare an array of pointers and then I call a function which splits a given sentence and then want to assign it to the array of pointers in main(). I am unable to do. Can you please check the code pasted below: int main(void) { char *data[3]; allocate(data); ...

Are ref and out in C# the same a pointers in C++?

I just made a Swap routine in C# like this: static void Swap(ref int x, ref int y) { int temp = x; x = y; y = temp; } It does the same thing that this C++ code does: void swap(int *d1, int *d2) { int temp=*d1; *d1=*d2; *d2=temp; } So are the ref and out keywords like pointers for C# without using unsafe code...

delphi pointer address

In Delphi: How do I get the address (0x2384293) a pointer points to? var iValue := Integer; iptrValue := PInteger; implementation procedure TForm1.Button1Click(Sender: TObject); begin iptrValue := @iValue; iValue := 32342; //Should return the same value: Edit1.Text := GetAddressOf(iptrValue); Edit2.Text := GetAddressOf(...

C++ - when should I use a pointer member in a class

One of the thing that has been confusing for me while learning C++ (and Direct3D, but that some time ago) is when you should use a pointer member in a class. For example, I can use a non-pointer declaration: private: SomeClass instance_; Or I could use a pointer declaration private: Someclass * instance_ And then use new() o...

Objective-C @interface/pointer clarification.

Learning as always, was going along quite nicely, until I realized I had no idea what the differences meant between these. @class Player; @class Map; @interface View : NSView { Player* player_; Map* currentMap_; NSMutableArray *worldArray; NSMutableArray *itemArray; float cellHeight_; } @end Never mind, turns out...

(C#) Is there a way to set the value of a single bit through pointers?

What I mean is: Imagine we have a 8 byte variable that has a high value and low value. I can make one pointer point to the upper 4 bytes and other point to the lower 4 bytes, and set/retrieve their values without problems. Now, is there a way to get/set values for anything smaller than a byte? If instead of dividing it in two 4 bytes "va...

Is it possible to define a pointer to a character inside a text file?

Say we have opened a text file. Is it possible to define a pointer to a character in the file? If it is - will the following characters in the file appear in memory in the same order they appear in the file? The reason I ask: I need to process a text file. I read one line at a time and there are certain strings I want to keep. The buffe...

Pointer to struct within the nested structs

Hello all, I'm trying to run the following code(in gcc 4.3 on fedora 11 i586 ): #include #include #include struct s_smallstruct{ int smallstruct; }; struct s_test2{ char * test2; struct s_smallstruct* smallstruct; }; struc...

Adding pointers

var Buffer: TMemoryStream The code: Move((PByte(Buffer.Memory)+Buffer.Position)^, Buffer.Memory^, Buffer.Size - Buffer.Position); Unfortunately this is not possible: Operator is not applicable to this type of operand. So how can I get the starting point of a MemoryBuffer? ...

What undefined behaviour does this C++ code contain

I wrote up this code after reading item 11 of Effective C++ ( Third Edition ). #include <iostream> using namespace std; #define MAX_COLORS 20 class Widget { public: Widget ( int seed ); ~Widget ( ); Widget& operator=( const Widget& rhs ); void ToString ( ); private: Widget& SelfAssignmentUnsafe ( const Widget& rh...

Memory Allocation Crash

I have stumbled accross a strange problem in which I cannot understand. I am not an expert at C/C++ so bear with me. I have an NPC class, which derives from a Player class, which derives from a Sprite class. The sprite class contains a setupAnimation function, which allocates an array of floats containing coordinates on the texture, each...

php copying array elements by value, not by reference

I have the following code: $data['x'] = $this->x->getResults(); $data['y'] = $data['x']; //some code here to modify $data['y'] //this causes (undesirably) $data['x] to be modified as well I guess since all the elements of $data are themselves references, modifying $data['y'] also modifies $data['x']..which is NOT what I want. I w...

C Pointer Question

In my embedded c program I have a struct: struct var{ unsigned long value; unsigned long length; + More } An array of these structs is used to hold variables. Most of the variables stored are simply stored in 'value' and so the length is set to 1. However, some of these variables are arrays and Im trying to store the star...

Delphi - structures' strings not being freed [FastMM manager]

If I declare PSomeStruct = ^TSomeStruct; TSomeStruct = record s1 : string; end; and I run the following code: var p: PSomeStruct; begin new(p); p^.s1:= 'something bla bla bla'; dispose(p); the FastMM 4 memory manager reports that there was a memory leak (type: string, data dump: "something bla bla bla"). However, if I ...

how can I save struct in file .... C lang

I'd like to save a struct in a file. I'd like to realize a function which makes this work. I tried this code but it didn't work. struct utilisateur // enregestrement pour sauvegarder les details de l utilisateur { char nom[20]; char prenom[20]; int place; char depart[20]; char arrive[20]; char sexe; int nwagon; }; struct uti...

Memory location of enum value in C

I think I've read somewhere that it is illegal to take the address of an enum value in C (enum values not being lvalues; however, I can't find any information on this now). Is that correct and, if so, why? Edit: Here's an example that clarifies what I mean by "enum value" above. I mean taking the address of first_value below, not tak...

Increment Pointer in Delphi / Create stream from pointer

Hi! Short form: Is it possible to create a stream from a pointer? I have a pointer which points to file data I need to read. I used WriteBuffer() to transfer data from the pointer to a TFileStream, which works. But now I want to read it block wise to display a progress bar. So I need to read it step by step. I have to options: 1) In...