programming problem in C++

#include "stdio.h"
#include "string.h"

#define MAX_STRING_LEN 100

int main() {
  char str[MAX_STRING_LEN + 1] = {0};
  int strl = 0;
  int move_count = 0;
  int move_pos = 0;
  int i = 0;

  scanf("%s", str);
  strl = strlen(str);  
  if(strl < 1) {
    printf("Empty string\n");
    return 0;
  }
  for(i = 0; i < strl; i++) {
    if((str[i] != '0') && (str[i] != '1')) {
      printf("Invalid character in string\n");
      return 0;
    }
  }

  for(i = strl -1, move_pos = strl - 1; i >= 0; i--) {
    if(str[i] == '1') {
      str[i] = '0';
      str[move_pos] = '1';
      move_count += move_pos - i;
      move_pos--;
    }
  }

  printf("Result string: %s\n", str);
  printf("Total movement: %d\n", move_count);

  return 0;
}