Show hex, bin, unsigned, signed content of a integer. *This is the helper program modified from code from CSAPP website.

showi.c

/* Display value of fixed point numbers */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

/* Extract hex/decimal/or float value from string */
static int get_num_val(char *sval, unsigned *valp) {
  char *endp;
  /* See if it's an integer or floating point */
  int isbinary = 0;
  int ishex = 0;
  int isfloat = 0;
  int i;
  for (i = 0; sval[i]; i++) {
    switch (sval[i]) {
    case 'b':
    case 'B':
      isbinary = 1;
      break;
    case 'x':
    case 'X':
      ishex = 1;
      break;
    case 'e':
    case 'E':
      if (!ishex || !isbinary)
	isfloat = 1;
      break;
    case '.':
      isfloat = 1;
      break;
    default:
      break;
    }
  }
  if (isfloat) {
    return 0; /* Not supposed to have a float here */
  } else if (isbinary){
    char* strwo0b = strchr(sval, 'b');    
    if(strwo0b == NULL)
      strwo0b = strchr(sval, 'B');
    strwo0b = strwo0b+1;
    long long int llval = strtoll(strwo0b,&endp,2);
    long long int upperbits = llval >> 31;
    /* will give -1 for negative, 0 or 1 for positive */
    if (valp && (upperbits == 0 || upperbits == -1 || upperbits == 1)) {
      *valp = (unsigned) llval;
      return 1;
    }
    return 0;
  } else {
    long long int llval = strtoll(sval, &endp, 0);
    long long int upperbits = llval >> 31;
    /* will give -1 for negative, 0 or 1 for positive */
    if (valp && (upperbits == 0 || upperbits == -1 || upperbits == 1)) {
      *valp = (unsigned) llval;
      return 1;
    }
    return 0;
  }
}
const char *int_to_binary(int x)
{
    static char b[33];
    b[0] = '\0';
int i;
    for (i=0; i <32; i++)
    {
        strcat(b,((x & (1<<(31-i))) != 0) ? "1" : "0");
    }
    return b;
}
void show_int(unsigned uf)
{
  printf("Bin = 0b%s\t,Hex = 0x%.8x,\tSigned = %d,\tUnsigned = %u\n",
	 int_to_binary(uf),uf, (int) uf, uf);
}


void usage(char *fname) {
  printf("Usage: %s val1 val2 ...\n", fname);
  printf("Values may be given in hex or decimal\n");
  exit(0);
}

int main(int argc, char *argv[])
{
  int i;
  unsigned uf;
  if (argc < 2)
    usage(argv[0]);
  for (i = 1; i < argc; i++) {
    char *sval = argv[i];
    if (get_num_val(sval, &uf)) {
      show_int(uf);
    } else {
      printf("Cannot convert '%s' to 32-bit number\n", sval);
    }
  }
  return 0;
}