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

int main (int argc, string argv[])

int i;

{

    //checking if te input has 2 arguments
    if (argc != 2 ) { printf("try to use 2 arguments\n"); return 1;
    }
    //convert argv to string "key"
    string key = argv[1];

    if (argc == 2)
    {
        //plaintext input
    string text = get_string("Enter plaintext: ");
        printf("ciphertext: ");

        // print out the plaintext letter by letter
        for (int i =0, n = strlen(text); i < n ; i++)

         // here is where I struggle, the sub script to wraparound the key only if its an alphabetic character.
        if isalpha(text[i])  {
          for (int keyindex = 0, nk = strlen(key); keyindex < nk; keyindex++)
            keyindex % nk;
             }

             // convert the plaintext to ciphertext

                if islower(text[i])
                    printf("%c", (((text[i] + key[keyindex]) - 97) % 26) + 97);
                else if isupper(text[i])
                    printf("%c", (((text[i] + key[keyindex]) - 65) % 26) + 65);

                else printf("%c",text[i]);

        printf("\n");
    }

}