How can I increase the image of bmp using c code only?

/****************************************************************************
 
 *
 * BMP-related data types based on Microsoft's own.
 ***************************************************************************/
 
 
/* 
 * Common Data Types 
 *
 * The data types in this section are essentially aliases for C/C++ 
 * primitive data types.
 *
 * Adapted from http://msdn.microsoft.com/en-us/library/cc230309.aspx.
 */
 
typedef unsigned char   BYTE;
typedef unsigned long   DWORD;
typedef long            LONG;
typedef unsigned short  WORD;
 
 
/*
 * BITMAPFILEHEADER
 *
 * The BITMAPFILEHEADER structure contains information about the type, size,
 * and layout of a file that contains a DIB [device-independent bitmap].
 *
 * Adapted from http://msdn2.microsoft.com/en-us/library/ms532321.aspx.
 */
 
typedef struct 
{ 
    WORD   bfType; 
    DWORD  bfSize; 
    WORD   bfReserved1; 
    WORD   bfReserved2; 
    DWORD  bfOffBits; 
} __attribute__((__packed__)) 
BITMAPFILEHEADER; 
 
 
/*
 * BITMAPINFOHEADER
 *
 * The BITMAPINFOHEADER structure contains information about the 
 * dimensions and color format of a DIB [device-independent bitmap].
 *
 * Adapted from http://msdn2.microsoft.com/en-us/library/ms532290.aspx.
 */
       
typedef struct
{
    DWORD  biSize; 
    LONG   biWidth; 
    LONG   biHeight; 
    WORD   biPlanes; 
    WORD   biBitCount; 
    DWORD  biCompression; 
    DWORD  biSizeImage; 
    LONG   biXPelsPerMeter; 
    LONG   biYPelsPerMeter; 
    DWORD  biClrUsed; 
    DWORD  biClrImportant; 
} __attribute__((__packed__))
BITMAPINFOHEADER; 
 
 
/* 
 * RGBTRIPLE
 *
 * This structure describes a color consisting of relative intensities of
 * red, green, and blue.
 *
 * Adapted from http://msdn.microsoft.com/en-us/library/aa922590.aspx.
 */
 
typedef struct
{
    BYTE  rgbtBlue;
    BYTE  rgbtGreen;
    BYTE  rgbtRed;
} __attribute__((__packed__))
RGBTRIPLE;
/****************************************************************************
 
 *
 
 * Copies a BMP piece by piece
 ***************************************************************************/
       
#include <stdio.h>
#include <stdlib.h>
 
#include "bmp.h"
 
 
int
main(int argc, char *argv[])
{
    // ensure proper usage
    if (argc != 4)
    {
        printf("Usage: resize number infile outfile\n");
        return 1;
    }
 
    // remember filenames
    int number = atoi(argv[1]);
    char *infile = argv[2];
    char *outfile = argv[3];
 
    // make sure it's postive number
    if (number < 0)
    {
        printf("Please enter a postive number\n");
        return 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)
    {
        fprintf(stderr, "Could not create %s.\n", outfile);
        return 3;
    }
 
    // read infile's BITMAPFILEHEADER
    BITMAPFILEHEADER bf;
    fread(&bf, sizeof(BITMAPFILEHEADER), 1, inptr);
 
    // read infile's BITMAPINFOHEADER
    BITMAPINFOHEADER bi;
    fread(&bi, sizeof(BITMAPINFOHEADER), 1, inptr);
 
    // 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)
    {
        fprintf(stderr, "Unsupported file format.\n");
        return 4;
    }
 
    // write outfile's BITMAPFILEHEADER
    fwrite(&bf, sizeof(BITMAPFILEHEADER), 1, outptr);
    printf("before bi.biWidth=%ld\n", bi.biWidth);
    bi.biWidth=bi.biWidth * number;     
    printf("after bi.biWidth=%ld\n", bi.biWidth);
    printf("before bi.biHeight=%ld\n", bi.biHeight);
    bi.biHeight=bi.biHeight * number; 
    printf("after bi.biHeight=%ld\n", bi.biHeight);
    printf("before bi.biSizeImage=%ld\n", bi.biSizeImage);
    bi.biSizeImage=bi.biSizeImage * number * number;
    printf("after bi.biSizeImage=%ld\n", bi.biSizeImage);
    // write outfile's BITMAPINFOHEADER
    fwrite(&bi, sizeof(BITMAPINFOHEADER), 1, outptr);
    
    unsigned char * buffer[1048576]={' '};
//    fread(&buffer, sizeof(RGBTRIPLE), 1, inptr);
   
 
         
    // determine padding for scanlines
    int padding =  ((4  - (bi.biWidth * sizeof(RGBTRIPLE)/number) % 4) * 
    (4  - (bi.biHeight * sizeof(RGBTRIPLE)/number) % 4)) % 4 ;
    printf("padding=%d\n", padding);
 
    printf("before bi.biHeight=%ld\n", bi.biHeight);
    //    bi.biHeight=bi.biHeight * number;
    //        printf("after bi.biHeight=%ld\n", bi.biHeight);
    
    // iterate over infile's scanlines
    for (int i = 0, biHeight = abs(bi.biHeight); i < biHeight/number; i++)
    {
        RGBTRIPLE triple;
 
        printf("i=%d\n",i);
//        printf("j=%d\n",j);
        fread(&triple, sizeof(RGBTRIPLE), 1, inptr);
        for (int m=0; m < number; m++)
        {
            fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
            printf("outside triple.rgbtBlue=%x\n",triple.rgbtBlue);
            printf("outside triple.rgbtGreen=%x\n",triple.rgbtGreen);
            printf("outside triple.rgbtRed=%x\n",triple.rgbtRed);
        }
        // iterate over pixels in scanline
        for (int j = 0; j < bi.biWidth/number; j++)
        {
        //    printf("i=%d\n",i);
            printf("j=%d\n",j);
            // temporary storage
          //  RGBTRIPLE triple;
 
            // read RGB triple from infile
            fread(&triple, sizeof(RGBTRIPLE), 1, inptr);
    //        buffer=triple;
      //      printf("buffer=%x\n",buffer);
            // write RGB triple to outfile
            for (int l=0; l < number; l++)
            {
               fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
               printf("inside triple.rgbtBlue=%x\n",triple.rgbtBlue);
               printf("inside triple.rgbtGreen=%x\n",triple.rgbtGreen);
               printf("inside triple.rgbtRed=%x\n",triple.rgbtRed);
            }
        }
      //  for (int m=0; m < number; m++)
      //  {
      //      fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
       //     printf("outside triple.rgbtBlue=%x\n",triple.rgbtBlue);
       //     printf("outside triple.rgbtGreen=%x\n",triple.rgbtGreen);
       //     printf("outside triple.rgbtRed=%x\n",triple.rgbtRed);
      //  }
        // skip over padding, if any
        fseek(inptr, padding, SEEK_CUR);
 
        // write padding to outfile
        for (int k = 0; k < padding; k++)
            fputc(0x00, outptr);
    }
 
    // close infile
    fclose(inptr);
 
    // close outfile
    fclose(outptr);
 
    // that's all folks
    return 0;
}