Convertit une Chaîne Binaire en C

Sans aucune des hypothèses à propos de l'entrée, juste l'impression de les bits dans les octets:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <errno.h>
char *stringToBinary(char *s)
{
if (s == NULL) {
//NULL might be 0 but you cannot be sure about it
return NULL;
}
//get length of string without NUL
size_t slen = strlen(s);
//we cannot do that here, why?
//if(slen == 0){ return s;}
errno = 0;
//allocate "slen" (number of characters in string without NUL)
//times the number of bits in a "char" plus one byte for the NUL
//at the end of the return value
char *binary = malloc(slen * CHAR_BIT + 1);
if(binary == NULL){
fprintf(stderr,"malloc has failed in stringToBinary(%s): %s\n",s, strerror(errno));
return NULL;
}
//finally we can put our shortcut from above here
if (slen == 0) {
*binary = '\0';
return binary;
}
char *ptr;
//keep an eye on the beginning
char *start = binary;
int i;
//loop over the input-characters
for (ptr = s; *ptr != '\0'; ptr++) {
/* perform bitwise AND for every bit of the character */
//loop over the input-character bits
for (i = CHAR_BIT - 1; i >= 0; i--, binary++) {
*binary = (*ptr & 1 << i) ? '1' : '0';
}
}
//finalize return value
*binary = '\0';
//reset pointer to beginning
binary = start;
return binary;
}
int main(int argc, char **argv)
{
char *output;
if (argc != 2) {
fprintf(stderr, "Usage: %s string\n", argv[0]);
exit(EXIT_FAILURE);
}
//TODO: check argv[1]
output = stringToBinary(argv[1]);
printf("%s\n", output);
free(output);
exit(EXIT_SUCCESS);
}

Je n'ai pas le compiler, mais j'espère que cela vous inspirera
Donc:
un char est de 8 bits.
xxxxxxxx
comparer chaque bit est plus facile et plus rapide avec un masque
xxxxxxxX
&
00000001
c'est vrai que si le 1er bit est à 1.
la prochaine sera
xxxxxxXx
&
00000010

char * stringToBinary( char * s )
{   
//Variables.
char * aux, *binary, mask;
int size, i, y;
if(s == NULL){
//If arg is null, nothing to do.
return NULL;
}
//Calculate the size of the str.
size= strlen(s);
//alloc the str that contain the answer.
binary= malloc( (size*8)+1 );
//If no memory, nothing to do.
if( binary == NULL ){
//No memory
return NULL;
}
//save a copy of the arg.
aux= s;
//for each char in the str arg.
for( i=0; i<size; i++ ){
//In each char to examinate, reset the mask.
mask= 0x0001;
//For each bit of a char.
for( y=0; y<8; y++ ){
//Compare each bit with the mask.
if( (*aux) & mask ){
//add 0 to the answer.
strcat(bynary,"1");
}else{
//add 1 to the answer.
strcat(bynary,"0");
}
//shit the mask 1 pos to left.
mask= mask<<1;
}
aux++
}
return binary;
}