fork download
copy 
  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4.  
  5. typedef struct
  6. {
  7.    size_t         len;
  8.    unsigned char* str;
  9. } HexString;
  10.  
  11. int hex_to_int(unsigned char c)
  12. {
  13.    int first =0;
  14.    int second =0;
  15.    int result=0;
  16.    if (c >= 97 && c <= 102) /* 97 = 'a'; 102 = 'f' */
  17.       c -= 32;
  18.    first  = c / 16 - 3;
  19.    second = c % 16;
  20.    result = first * 10 + second;
  21.    if (result > 9) result--;
  22.    return result;
  23. }
  24.  
  25. unsigned char hex_to_ascii(unsigned char c, unsigned char d)
  26. {
  27.    unsigned char a = '0';
  28.    int high = hex_to_int(c) * 16;
  29.    int low  = hex_to_int(d);
  30.    a = high + low;
  31.    return a;
  32. }
  33.  
  34. HexString HextoString(const char* const st)
  35. {
  36.    HexString result;
  37.    size_t length = strlen(st);
  38.    result.len = length/2+1;
  39.    result.str = malloc(length/2+1);
  40.    size_t i;
  41.    size_t j = 0;
  42.    unsigned char buf = 0;
  43.    for (i = 0; i < length; i++)
  44.    {
  45.       if (i % 2 != 0)
  46.       {
  47.          result.str[j++] = hex_to_ascii(buf, st[i]);
  48.       }
  49.       else
  50.       {
  51.          buf = (unsigned char)st[i];
  52.       }
  53.    }
  54.    result.str[length/2+1] = '\0';
  55.    return result;
  56. }
  57.  
  58. int main()
  59. {
  60.    size_t i;
  61.    HexString hexString = HextoString("0a12345600a0020b12");
  62.    for (i = 0; i < hexString.len; ++i)
  63.    {
  64.       printf("<%02x> ", hexString.str[i]);
  65.    }
  66.  
  67.    free(hexString.str);
  68.  
  69.    return 0;
  70. }
Success #stdin #stdout 0s 10320KB
comments ()
stdin
copy 
Standard input is empty
stdout
copy 
<0a> <12> <34> <56> <00> <a0> <02> <0b> <12> <00>
https://ideone.com/pLI1hO
language:
C (gcc 8.3)
created:
7 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!