text2hex

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

char *text2hex(const char *const string) {
  const int n = strlen(string);
  char *hex = malloc(sizeof(char) * (n * 2 + 1));
  if (hex == NULL) {
    fprintf(stderr, "failed to alloc!\n");
    exit(EXIT_FAILURE);
  }
  hex[0] = 0;
  for (int i = 0; i < n; i++) {
    char aux[2] = {};
    sprintf(aux, "%x", (int)string[i]);
    strcat(hex, aux);
  }
  return hex;
}

int main(void) {
  char s[] = "abc", *res = NULL;
  res = text2hex(s);
  puts(res);
  free(res);
  return 0;
}