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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4.  
  5. const char *string2bin_ar[] = {
  6.         "0000", // 0
  7.         "0001", // 1
  8.         "0010", // 2
  9.         "0011", // 3
  10.         "0100", // 4
  11.         "0101", // 5
  12.         "0110", // 6
  13.         "0111", // 7
  14.         "1000", // 8
  15.         "1001", // 9
  16.         "1010", // A
  17.         "1011", // B
  18.         "1100", // C
  19.         "1101", // D
  20.         "1110", // E
  21.         "1111", // F
  22.         };
  23.  
  24.  
  25. char *
  26. string2binstr(char *hexstring) {
  27.         size_t len = strlen(hexstring);
  28.         size_t idx = 0;
  29.         unsigned char no;
  30.         char *out;
  31.         if (!len) {
  32.                 fprintf(stderr, "string2bin: no input data");
  33.                 return NULL;
  34.         }
  35.         /* string can't be less then 32 bits (chars in sample)
  36.          * 32 (minimum length) / 4 (hex chunk length) = 8 (number of hex chuncks) */
  37.         out = calloc(1, (len < 8 ? 32 : len * 4 ) + 1);
  38.         if (!out) {
  39.                 fprintf(stderr, "string2bin: no enough memory\n");
  40.                 return NULL;
  41.         }
  42.         out[len * 4] = '\0';
  43.         for (; idx < len; idx++) {
  44.                 no = (unsigned char)hexstring[idx];
  45.                 if (no >= '0' && no <= '9')
  46.                         no -= '0';
  47.                 else if (no >= 'A' && no <= 'F')
  48.                         no -= ('A' - 10);
  49.                 else if (no >= 'a' && no <= 'f')
  50.                         no -= ('a' - 10);
  51.                 else no = 0;
  52.                 memcpy(&out[idx * 4], string2bin_ar[no], 4);
  53.         }
  54.         /* fill missing bits (bytes) */
  55.         if (idx < 8)
  56.                 memset(&out[idx * 4], '0', 32 - idx * 4);
  57.         return out;
  58. }
  59.  
  60. int main(int argc, char *argv[])
  61. {
  62. 	printf("%s\n", string2binstr("FF"));
  63.  
  64. 	return 0;
  65. }
Success #stdin #stdout 0s 2424KB
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stdin
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Standard input is empty
stdout
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11111111000000000000000000000000
https://ideone.com/sSKC9U
language:
C (gcc 8.3)
created:
10 years ago
visibility:
public

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