Mirror image read from 2D array in C - c

Question

I am writting a program in C in which i'm reading a bmp image with a 2D array. I am supposed to have as output the original image + its inverse right next to each other.
The code I have here should be doing that but the images print on top of each other. I appreciate the help if anyone knows how I can fix that.
int main(void) {
// Opens file to read the image from
FILE * infile = fopen("inputImage.bmp", "rb");
// Creates file to write the image to after modifications
FILE * outfile = fopen("flip.bmp", "wb");
//Bmp images have headers the next 3 lines of code store the header of the input image
unsigned char headersPart1[2];
int filesize;
unsigned char headersPart2[48];
// This space[] [] creates the array to which to write the input image AND its inverse right next to each other the image file is 160 * 240
// The 3 is for the rgb values.. since its a 2D array we want to use every single //part of the image to work with
unsigned char space[160][3*240];
//The array to which to copy the results to (original image + INVERSE)
unsigned char mirror[160][3*480];
fread(headersPart1,sizeof(char) ,2,infile);
fread(&filesize,sizeof(char) ,4,infile);
fread(headersPart2,sizeof(char) ,48,infile);
fread(space,sizeof(char) ,filesize-54,infile);
// copying what in the original image array (space[][]) into the new //array mirror[][]
for ( int row = 0; row < 240*3 ; row++ ) {
for (int col = 0 ; col < 160; col++) {
char temp = space[col][row];
mirror[col][row] = space[col][row];
//Starts printing the inverse of the original image, starting at the index where the original image will end
mirror[col][720+row]= space[col][719-row];
space[col][row] = temp;
}
}
// Puts everything back into the outfile , once i save and run on GCC this gives me an image and its inverse on top of each other
fwrite(headersPart1,sizeof(char) ,2,outfile);
fwrite(&filesize,sizeof(char) ,4,outfile);
fwrite(headersPart2,sizeof(char) ,48,outfile);
//sends whats in mirror [][] to the outfile
//54 is the size of the header (bmp images))
fwrite(mirror,sizeof(char) ,filesize-54,outfile);
return 0;
}
PS: I'm running this on GCC

Answer 1

The BMP file format you can find here
Your loader is not complete regarding support different versions of BMP, check resolution, color-depth, the presens of palette etc.
But for what you want to use this for, you probably have a fixed input, always the same resolution etc.
But you want the resulting image to be twice as wide. Hence some details in the headers has to change:
"filesize"
"the bitmap width in pixels (signed integer)"