#include <cs50.h>
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>

bool only_digits(string);
int main(int argc, string argv[])
{
//Get key//
//Preserve capital/lower case letter, spaces, punctuations//
//Print out usage message if user don't comply (two arguments)//
if(argc != 2)
{
  printf("Usage: ./caesar keyn");
  return 1;
}
else
{
  return 0;
}
// Print out usage message if user don't comply (only digits)//
bool a = only_digits(argv[1]);
if (only_digits(argv[1]) == false)
{
  printf("Usage: ./caesar keyn");
  return 1;
}
else
{
  return 0;
}

}
bool only_digits(string s)
{
  for (int i = 0, len = strlen(s); i < len ; i++)
  {

    if (!isdigit(s[i]))
    {
      return false;
    }
  }
  return true;
}

unable to get the result i was trying to get when i type in my command line arguments

eg ./caesar banana
supposed to get: Usage: ./caesar key and programme exits due to return 1
got: programme just continues and no “error msg”