bin-to-asc.c

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

int to_dec(char *bin) {
  unsigned int dec = 0;
  unsigned int weight = 1;
  bin += 8 - 1;
  for(int i=0; i<8; i++, --bin) {
    if(*bin == '1') {
      dec += weight;
    }
    weight *= 2;
  }
  return dec;
}

int main(int argc, char *argv[]) {
  if (argc != 2 || strlen(argv[1]) % 8 != 0 || strlen(argv[1]) == 0) {
    printf("err: input not divisible by 8 or is 0\n");
    exit(1);
  }
  char buf[8];
  for(int i=0; i<strlen(argv[1]); i+=8) {
    for(int j=0; j<8; j++) {
      buf[j] = argv[1][i+j];
    }
    printf("%c", (char)to_dec(buf));
  }
  printf("\n");
  return 0;
}