Display HEX and Binary representation of an integer with C
a little example in C on how to display an integer in hex an binary:
/**
* Name : bitwise.c
* Author : wus
* Version : $Id: bitwise.c 13 2012-04-23 15:37:41Z wus $
* Copyright : GPL
* Description : Print an 8-64 bit integer in hex and binary to stdout.
*
* NOTE: gcc needs the -lm option enabled to include the math library (must add
* -lm after the source file, WTF?)
* NOTE: compile flags: $ gcc -ofilename filename.c -lm
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <math.h>
int int_size = 64; // num bits of integer
void usage(void) {
printf("Usage: bitwise <%d bit int>\n\n", int_size);
printf("Exit codes:\n");
printf(" 2 argument error\n");
printf(" 3 overflow error\n");
}
char dec2hex(int digit) {
if (digit < 10) return (digit + 48);
switch(digit) {
case 10: return 'A';
case 11: return 'B';
case 12: return 'C';
case 13: return 'D';
case 14: return 'E';
case 15: return 'F';
}
return '*';
}
/**
* generate binary and hex string from an integer
*
* loop bit for bit (MSB) over an integer, generate binary and hex string
*
* param num: the number
* param result: max. 64 bits + 7 spaces (pairs by 4 and an ending \0
* param hex: hex representation, 8 digits and one \0
* param int_size: number of bits to represent in the output
*/
void format_bin(uint64_t num, char result[78], char hex[9], int int_size) {
int pos_bit, pos_string = 0;
int pos_hex = int_size / 4 - 1;
int str_size = int_size + (int_size/4 - 1);
hex[pos_hex] = 0;
for(pos_bit=0; pos_bit < int_size; pos_bit++, pos_string++) {
// add spaces
if (pos_bit % 4 == 0 && pos_bit != 0) {
result[str_size - 1 - pos_string++] = ' ';
}
// check if current bit is set
int t = ((num & (1L<<pos_bit)) ? 1 : 0);
result[str_size - 1 - pos_string] = t + 48;
// handle hex
int pot = pos_bit % 4;
if (t) {
switch (pot) {
case 0: hex[pos_hex] += 1; break;
case 1: hex[pos_hex] += 2; break;
case 2: hex[pos_hex] += 4; break;
case 3: hex[pos_hex] += 8; break;
}
}
// next character
if (pot == 3) {
// make sure the int is a character and store it in the
// result hex string
hex[pos_hex] = dec2hex(hex[pos_hex]);
hex[--pos_hex] = 0;
}
} // end for loop
hex[int_size/4] = '\0';
result[str_size] = '\0';
}
/**
* generate binary and hex representation of an integer value
*/
int main(int argc, char* argv[]) {
if (argc != 2) {
usage();
exit(2);
}
int arg1 = atoi(argv[1]);
// check overflow
if (arg1 > (pow(2, int_size) - 1)) {
printf("Overflow detected, we can handle max. %d bit integers!\n\n",
int_size);
usage();
exit(3);
}
uint8_t input = arg1;
char str[78];
char hex[9];
format_bin(input, str, hex, int_size);
printf("\n0x%s - %s\n", hex, str);
return EXIT_SUCCESS;
}
