error C2664: cannot convert parameter 1 from float** __w64 to float *

Hi,

simply put the following code generates the error

Code:

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error C2664: 'vGetPixelValueIntoArray' : cannot convert parameter 1 from 'float **__w64  ' to 'float *'

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Code:

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int main(int argc, char **argv) {
 
float **ppfImageData;/* a pointer to a series of 2d arrays */
s_Filename *psFile;
s_Header *psHeader;
       
psFile = (struct s_Filename *) malloc(sizeof(s_Filename));
psHeader = (struct s_Header *) malloc(sizeof(s_Header));

if (argc < 2){strncpy(acFilename, "C:\\Documents and Settings\\matt smith\\Desktop\\example\\img0061.ppm", sizeof(acFilename));}
else {strncpy(acFilename,argv[1],sizeof(acFilename));}

psFile = psGetImageBase(acFilename, psFile); //not important
psHeader = psGetHeader(psFile->acNextFileName, psHeader); //not important

psHeader->nPhotosToBeCounted = psFile->nMaxImagenumber;

        if(!(ppfImageData = (float **) malloc(psHeader->nPhotosToBeCounted))){
        fprintf(stderr, "Failed to allocate memory for imageMatrix array!\n");
                return NULL;
        }

vGetPixelValueIntoArray(&ppfImageData[nCountI], psFile->acNextFileName, psHeader); //this is the line that causes the error (the &ppfImageData is the problem variable)

}

void vGetPixelValueIntoArray(float *pfImageData, const char* pccFilename, s_Header* psHeader ) {// returns NULL if error
    size_t nCounter, nSecondCounter;
    FILE *pFTemp_file;

        psHeader->nWantedPixels = 5;

        if (!(pfImageData = (float *) malloc(psHeader->nWantedPixels))){ //malloc array for image data
        fprintf(stderr, "Failed to allocate memory in *pfGetPixelValueIntoArray");
        exit(-1);
    }       
}

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I have looked into this problem and it could be a win32 problem but I have tried all of the suggestions about pre-processing I could find, was wondering if anyone had any ideas where I was going wrong...


Cheers,
Giant

Consider:

Code:

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void foo( int *bar );

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Now if you want to pass an integer to this you do this:

Code:

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int baz;

foo( &baz );

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And if we want to pass an actual pointer pointer:

Code:

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int *baz;

foo( baz );

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And if we're going from a pointer to a pointer:

Code:

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int **baz;

foo( *baz );

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And if we're pretending our two pointers are an array:

Code:

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int **baz;

foo( baz[ x ] );

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Do you see your problem now?


Quzah.

erm...:( no sorry, can you take out the large stick of education and hit me with it please

from what I think you are saying I should pass

Code:

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vGetPixelValueIntoArray(ppfImageData[nCountI], psFile->acNextFileName, psHeader);

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instead of

Code:

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vGetPixelValueIntoArray(&ppfImageData[nCountI], psFile->acNextFileName, psHeader);

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If this is C, why are all those casts there?

define 'all those casts' ?

Well "all those casts" are on the return result of malloc.
In C,
psFile = malloc(sizeof(s_Filename));
Is all you need.

If you're getting warnings, then tell us what they are and we'll tell you how to fix it. Don't just sweep the warnings under the carpet to make them go away.

Just so we're straight, you want vGetPixelValueIntoArray to allocate some memory for a row of your array, and you want ppfImageData[nCountI] to be assigned the result of that malloc?

yes thats what i want to do and I have no warnings at all, just the error line

Giant.

[EDIT] When I take out the casts the compiler fails on all three counts saying ''cannot convert from void* to <insert cast here>''

I am using visual studio 2003 btw, incase thats important

[/EDIT]

i have shortened the code to isolate the problem to this:

Code:

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// OneChannelWin32.cpp : Defines the entry point for the console application.
//
#include <iostream>
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "ctype.h"
using namespace std;


//float *pfGetPixelValueIntoArray(const char*, s_Header*);
void vGetPixelValueIntoArray(float *);

void vGetPixelValueIntoArray(float *pfImageData ) {// returns NULL if error

        if (!(pfImageData = (float *) malloc(5))){ //malloc array for image data
        fprintf(stderr, "Failed to allocate memory in *pfGetPixelValueIntoArray");
        exit(-1); //cant return a null >???? need a error function
    }       
       
}

int main() {
 
        float **ppfImageData;/* a pointer to a series of 2d arrays */
        int photostobecounted=16, nCountJ=0;
       
        if(!(ppfImageData = (float **) malloc(photostobecounted))){
        fprintf(stderr, "Failed to allocate memory for imageMatrix array!\n");
                return NULL;
        }
                vGetPixelValueIntoArray(&ppfImageData[0]); //so mallocing the first

        // deallocate memory
        for (nCountJ=0; nCountJ<photostobecounted; nCountJ++){
                        free(ppfImageData[nCountJ]);
    }
    free(ppfImageData);
    return 0;
}

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> saying ''cannot convert from void* to <insert cast here>''
Yeah, that means you're using a C++ compiler to compile C code.
1. rename your files to be .c files (not .cpp files)
2. start using C++ properly and call new/delete to allocate memory, not malloc/free

But I see from your code, it's more C++ than C

Given your call, try this

Code:

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void vGetPixelValueIntoArray(float **);

void vGetPixelValueIntoArray(float **pfImageData ) {// returns NULL if error
    float *temp;
    if ( ! (temp = malloc(5*sizeof(*temp)) ) )
        fprintf(stderr, "Failed to allocate memory in *pfGetPixelValueIntoArray");
    *pfImageData = temp;
}

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