Answers for "hexdump in c"

hexdump in c

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

 void hexdump(unsigned char *buffer, unsigned long index, unsigned long width)
 {
  unsigned long i;
  for (i=0;i<index;i++)
	{
	printf("%02x ",buffer[i]);
	}
  for (unsigned long spacer=index;spacer<width;spacer++)
	printf("	");
  printf(": ");
  for (i=0;i<index;i++)
	{
	if (buffer[i] < 32) printf(".");
	else printf("%c",buffer[i]);
	}
  printf("\n");
 }

 int hexdump_file(FILE *infile,unsigned long start, unsigned long stop, unsigned long width)
  {
  char ch;
  unsigned long f_index=0;
  unsigned long bb_index=0;
  unsigned char *byte_buffer = malloc(width);
  if (byte_buffer == NULL)
	{
	printf("Could not allocate memory for byte_buffer\n");
	return -1;
	}
  while (!feof(infile))
	{
	ch = getc(infile);	
	if ((f_index >= start)&&(f_index <= stop))
	{
	 byte_buffer[bb_index] = ch;
	 bb_index++;
	}
	if (bb_index >= width)
	{
	  hexdump(byte_buffer,bb_index,width);
	  bb_index=0;
	}	
	f_index++;	
	}
  if (bb_index)
	hexdump(byte_buffer,bb_index,width);
  fclose(infile);
  free(byte_buffer);
  return 0;
 }

 int main(int argc, char *argv[])
 {
  if (argc != 5)
	{
	printf("Usage: hexdump <infile> <start> <end> <width>\n");
	return 0;
	}
  FILE *infile=fopen(argv[1],"rb");
  if (infile==(FILE *)NULL)
	{
	printf("Error opening input file %s\n",argv[1]);
	return 0;
	}
  printf("Filename: \"%s\"\n",	argv[1]);
  printf("Start : %lu\n",	atoi(argv[2]));
  printf("End	: %lu\n",	atoi(argv[3]));
  printf("Bytes per Line: %lu\n",atoi(argv[4]));  
  int result = hexdump_file(infile,atoi(argv[2]),atoi(argv[3]),atoi(argv[4]));
  return 0;
 }