Copying one bmp file to another using fstream, Access violation reading location er

[zwierzak]

I would like to copy one bmp file to another using plain fstream (none 3-rd party library). I've managed to come up with something but I keep getting error:

Unhandled exception at 0x504A3442 (msvcr120d.dll) in ConsoleApplication1.exe: 0xC0000005: Access violation reading location 0x00380000.

when i try to write the content of the bmp files not the header, namely error occurs in this line:

ofs_differential.write((char*)&picture, (bfh_warm.bfSize - bfh_warm.bfOffBits));

Also i am not sure if i am doing it in a right way, meaning that even after solving this error i will copy the bmp file sucessfully.

Code:

// ConsoleApplication1.cpp : Defines the entry point for the console application.
    //
    #include "stdafx.h"
    #include <iostream>
    #include <fstream>
    
    
    using namespace std;
    
    struct BITMAPfileHEADER
    {
    	unsigned short bfType;
	    unsigned int   bfSize;
    	unsigned short bfReserved1;
	    unsigned short bfReserved2;
	    unsigned int   bfOffBits;
    };
    
    
    struct BITMAPinfoHEADER
    {
    	unsigned int biSize;
	    unsigned int biWidth;
    	unsigned int biHeight;
    	unsigned short biPlanes;
    	unsigned short biBitCount;
    	unsigned int biCompression;
    	unsigned int biSizeImage;
    	unsigned int biXpelsPerMeter;
    	unsigned int biYpelsPerMeter;
    	unsigned int biClrUses;
    	unsigned int biClrImportant;
    };

    int readBFH(ifstream &ifs, BITMAPfileHEADER &bfh)
    {
    	ifs.read(reinterpret_cast<char *>(&bfh.bfType), 2);
    	ifs.read(reinterpret_cast<char *>(&bfh.bfSize), 4);
    	ifs.read(reinterpret_cast<char *>(&bfh.bfReserved1), 2);
    	ifs.read(reinterpret_cast<char *>(&bfh.bfReserved2), 2);
    	ifs.read(reinterpret_cast<char *>(&bfh.bfOffBits), 4);
    	return ifs.tellg();
    }
    int readBIH(ifstream &ifs, BITMAPinfoHEADER &bih)
    {
    	ifs.read(reinterpret_cast<char *>(&bih.biSize), 4);
    	ifs.read(reinterpret_cast<char *>(&bih.biWidth), 4);
    	ifs.read(reinterpret_cast<char *>(&bih.biHeight), 4);
    	ifs.read(reinterpret_cast<char *>(&bih.biPlanes), 2);
    	ifs.read(reinterpret_cast<char *>(&bih.biBitCount), 2);
    	ifs.read(reinterpret_cast<char *>(&bih.biCompression), 4);
    	ifs.read(reinterpret_cast<char *>(&bih.biSizeImage), 4);
    	ifs.read(reinterpret_cast<char *>(&bih.biXpelsPerMeter), 4);
    	ifs.read(reinterpret_cast<char *>(&bih.biYpelsPerMeter), 4);
    	ifs.read(reinterpret_cast<char *>(&bih.biClrUses), 4);
    	ifs.read(reinterpret_cast<char *>(&bih.biClrImportant), 4);    
    
	    return ifs.tellg();
    }
    
    char* readPictureData(ifstream &ifs, unsigned int size, int cursor)
    {
	    ifs.seekg(cursor, ios::beg);
	    char *picture = new char[size];
	    ifs.read(reinterpret_cast<char *>(picture), size);
	    return picture;
    }
    
    int main()
    {
    	BITMAPfileHEADER bfh_warm;
    	BITMAPfileHEADER bfh_cold;    

    	BITMAPinfoHEADER bih_warm;
    	BITMAPinfoHEADER bih_cold;

    	int cursor_warm;
    	int cursor_cold;

    	ifstream ifs_warm("1.bmp", ios::binary);
	    ifstream ifs_cold("2.bmp", ios::binary);
    
	    ofstream ofs_differential("differential.bmp", ofstream::binary);
    

	    cursor_warm = readBFH(ifs_warm, bfh_warm);
    	cursor_warm = readBIH(ifs_warm, bih_warm);
    	cursor_cold = readBFH(ifs_cold, bfh_cold);
    	cursor_cold = readBIH(ifs_cold, bih_cold);
    	char* picture = readPictureData(ifs_warm, bfh_warm.bfSize - bfh_warm.bfOffBits, bfh_warm.bfOffBits);


    	ofs_differential.write((char*)&bfh_warm, sizeof(bfh_warm)); //write header
	    ofs_differential.write((char*)&bih_warm, sizeof(bih_warm)); //write header
    	ofs_differential.write((char*)&picture, (bfh_warm.bfSize - bfh_warm.bfOffBits));
	    ifs_warm.close();
	    ifs_warm.close();
	    ofs_differential.close();
	    return 0;
    }

[Alex F]

ofs_differential.write((char*)picture, ...);

picture is already pointer, remove unnecessary &

[zwierzak]

Ok it helped, it was my mistake i didn't notice this little thing ;P

However, the header of the output file seems to be corrupted, because it's what i get when i try to open the output image. Does anyone happen to know why?

[Philip Nicoletti]

Something to check:

ofs_differential.write((char*)&bfh_warm, sizeof(bfh_warm) ); //write header

What is sizeof(bfh_warm) ? Is it 14, or 16 ?

Visual C++ has bitmap header structures you might use: BITMAPFILEHEADER and BITMAPINFOHEADER