I've been reluctant to ask for help but it's got to the stage where I'm all out of ideas. I just cannot get resize to pass check50.

The code looks fine, and when I run it through debug step by step, everything appears to be doing what it should be. I ran it through valgrind, too, just to make sure that there weren't any memory leaks or errors.

Here's my resize.c code:

#include <stdio.h> #include <stdlib.h>

#include "bmp.h"

int main(int argc, char* argv[]) { // ensure proper usage if (argc != 4) { printf("Usage: ./copy infile outfile\n"); return 1; } else if (atoi(argv[1]) < 1 || atoi(argv[1]) > 100) { printf("Your multiplier should be a number between 1 and 100\n"); return 1; }

// remember filenames
char* infile = argv[2];
char* outfile = argv[3];
int n = atoi(argv[1]); 

// open input file 
FILE* inptr = fopen(infile, "r");
if (inptr == NULL)
{
    printf("Could not open %s.\n", infile);
    return 2;
}

// open output file
FILE* outptr = fopen(outfile, "w");
if (outptr == NULL)
{
    fclose(inptr);
    fprintf(stderr, "Could not create %s.\n", outfile);
    return 3;
}

// read infile's BITMAPFILEHEADER
BITMAPFILEHEADER bf, new_bf;
fread(&bf, sizeof(BITMAPFILEHEADER), 1, inptr);
new_bf = bf;

// read infile's BITMAPINFOHEADER
BITMAPINFOHEADER bi, new_bi;
fread(&bi, sizeof(BITMAPINFOHEADER), 1, inptr);
new_bi = bi;



// ensure infile is (likely) a 24-bit uncompressed BMP 4.0
if (bf.bfType != 0x4d42 || bf.bfOffBits != 54 || bi.biSize != 40 || 
    bi.biBitCount != 24 || bi.biCompression != 0)
{
    fclose(outptr);
    fclose(inptr);
    fprintf(stderr, "Unsupported file format.\n");
    return 4;
}



// update height and width for header files
new_bi.biHeight *= n;
new_bi.biWidth *= n;

// determine padding for scanlines
int padding =  (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
int new_padding = (4 - (new_bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;

// new image and file sizes
new_bi.biSizeImage = ((new_bi.biWidth * sizeof(RGBTRIPLE) + new_padding) * abs(new_bi.biHeight);
new_bf.bfSize = new_bi.biSizeImage + sizeof(BITMAPINFOHEADER) + sizeof(BITMAPFILEHEADER);



// write outfile's BITMAPFILEHEADER
fwrite(&new_bf, sizeof(BITMAPFILEHEADER), 1, outptr);

// write outfile's BITMAPINFOHEADER
fwrite(&new_bi, sizeof(BITMAPINFOHEADER), 1, outptr);



// iterate over infile's scanlines
for (int i = 0, new_biHeight = abs(new_bi.biHeight); i < new_biHeight; i++)
{
    // loop for n number of lines
    for (int l = 0; l < n; l ++)
    {
        // iterate over pixels in scanline
        for (int j = 0; j < bi.biWidth; j++)
        {
          // temporary storage
            RGBTRIPLE triple;

            // read RGB triple from infile
            fread(&triple, sizeof(RGBTRIPLE), 1, inptr);
        
            // write RGB triple to outfile n times for horizontal

            for (int k = 0; k < n; k ++)
            {
                fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
            }
        }
        // skip over padding, if any
        fseek(inptr, padding, SEEK_CUR);

        // then add it back (to demonstrate how)
        for (int k = 0; k < new_padding; k++)
        {
            fputc(0x00, outptr);
        }
        
        // jump back to start of line while l is less than n-1
        if (l < n-1)
        {
            fseek(inptr, -(padding + (bi.biWidth * sizeof(RGBTRIPLE) ) ), SEEK_CUR);
        }
    }
}

// close infile
fclose(inptr);

// close outfile
fclose(outptr);

// that's all folks
return 0;

}

I've been reluctant to ask for help but it's got to the stage where I'm all out of ideas. I just cannot get resize to pass check50.

The code looks fine, and when I run it through debug step by step, everything appears to be doing what it should be. I ran it through valgrind, too, just to make sure that there weren't any memory leaks or errors.

Here's my resize.c code:

#include <stdio.h>
#include <stdlib.h>

#include "bmp.h"

int main(int argc, char* argv[])
{
    // ensure proper usage
    if (argc != 4)
    {
        printf("Usage: ./copy infile outfile\n");
        return 1;
    }
    else if (atoi(argv[1]) < 1 || atoi(argv[1]) > 100)
    {
        printf("Your multiplier should be a number between 1 and 100\n");
        return 1;
    }

    // remember filenames
    char* infile = argv[2];
    char* outfile = argv[3];
    int n = atoi(argv[1]); 

    // open input file 
    FILE* inptr = fopen(infile, "r");
    if (inptr == NULL)
    {
        printf("Could not open %s.\n", infile);
        return 2;
    }

    // open output file
    FILE* outptr = fopen(outfile, "w");
    if (outptr == NULL)
    {
        fclose(inptr);
        fprintf(stderr, "Could not create %s.\n", outfile);
        return 3;
    }

    // read infile's BITMAPFILEHEADER
    BITMAPFILEHEADER bf, new_bf;
    fread(&bf, sizeof(BITMAPFILEHEADER), 1, inptr);
    new_bf = bf;

    // read infile's BITMAPINFOHEADER
    BITMAPINFOHEADER bi, new_bi;
    fread(&bi, sizeof(BITMAPINFOHEADER), 1, inptr);
    new_bi = bi;

    // ensure infile is (likely) a 24-bit uncompressed BMP 4.0
    if (bf.bfType != 0x4d42 || bf.bfOffBits != 54 || bi.biSize != 40 || 
        bi.biBitCount != 24 || bi.biCompression != 0)
    {
        fclose(outptr);
        fclose(inptr);
        fprintf(stderr, "Unsupported file format.\n");
        return 4;
    }

    // update height and width for header files
    new_bi.biHeight *= n;
    new_bi.biWidth *= n;

    // determine padding for scanlines
    int padding =  (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
    int new_padding = (4 - (new_bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;

    // new image and file sizes
    // TODO: a paren is missing from this line!
    new_bi.biSizeImage = ((new_bi.biWidth * sizeof(RGBTRIPLE) + new_padding) * abs(new_bi.biHeight);
    new_bf.bfSize = new_bi.biSizeImage + sizeof(BITMAPINFOHEADER) + sizeof(BITMAPFILEHEADER);

    // write outfile's BITMAPFILEHEADER
    fwrite(&new_bf, sizeof(BITMAPFILEHEADER), 1, outptr);

    // write outfile's BITMAPINFOHEADER
    fwrite(&new_bi, sizeof(BITMAPINFOHEADER), 1, outptr);



    // iterate over infile's scanlines
    for (int i = 0, new_biHeight = abs(new_bi.biHeight); i < new_biHeight; i++)
    {
        // loop for n number of lines
        for (int l = 0; l < n; l ++)
        {
            // iterate over pixels in scanline
            for (int j = 0; j < bi.biWidth; j++)
            {
                // temporary storage
                RGBTRIPLE triple;

                // read RGB triple from infile
                fread(&triple, sizeof(RGBTRIPLE), 1, inptr);

                // write RGB triple to outfile n times for horizontal
                for (int k = 0; k < n; k ++)
                {
                    fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
                }
            }
            // skip over padding, if any
            fseek(inptr, padding, SEEK_CUR);

            // then add it back (to demonstrate how)
            for (int k = 0; k < new_padding; k++)
            {
                fputc(0x00, outptr);
            }

            // jump back to start of line while l is less than n-1
            if (l < n-1)
            {
                fseek(inptr, -(padding + (bi.biWidth * sizeof(RGBTRIPLE) ) ), SEEK_CUR);
            }
        }
    }

    // close infile
    fclose(inptr);

    // close outfile
    fclose(outptr);

    // that's all folks
    return 0;
}