Caesar

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



int main (int argc ,char* argv[])
{

    if (argc != 2)
    {
        printf("Try again");
        return 1;
    }

    int key = atoi(argv[1]); /// Get key turn it into an Int

    string p = GetString();
    char sum[strlen(p)]; /// Declare the string length of p as char


    for ( int i = 0, n = strlen(p);i < n; i++) /// Iterate over the string length of p and print enciphered code
   {
       if isalpha(p[i])
       {
           if isupper(p[i])
           {
               sum[i] = (p[i] - 'A' + key) % 26 + ('A');
           }
           else if islower(p[i])
           {
               sum[i] = (p[i] - 'a' + key) % 26 +('a');
           }
           else
           {
                sum[i] = p[i];
           }
       }
   }
    printf("%s\n",sum);
    return 0;
}