vigenere.c - shared from CS50 IDE

vigenere.c

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

int c;
int k1;
int p1;

int main(int argc, string argv[]) {
    if (argc != 2) {
        printf ("ERROR\n");
       return 1;
    }
    
    for (int i= 0, n = strlen(argv[1]); i < n; i++) {
        if (!isalpha (argv[1][i])) {
            printf ("ERROR\n");
            return 1;
        }
        
    }
    
     
     
     printf("plaintext:");
     string p = GetString();
     
     printf ("ciphertext:");
     
     
     for (int i = 0, n = strlen(p); i < n; i++) { //beginning for loop
                
                if (isupper (argv[1][i])) { //transforming iterated "key" elements in alphabetical order
                    k1 = argv[1][i] - 65;
                }
                else if (islower (argv[1][i])) {
                    k1 = argv[1][i] - 97;
                }

            
            
            
            if (isalpha (p[i])) {       //adding alphabetically ordered letter and then convert them i ASCII encrypted values

                if (isupper (p[i])) {
                    
                    p1 = p[i] - 65;
                    c = (p1 + k1)%26 + 65;
                    printf ("%c",  c);
                }
                
                else if (islower (p[i])) {
                    p1 = p [i] - 97;
                    c = (p1 + k1)%26 + 97;
                    printf ("%c",  c);
                }
                
            }
            if (isdigit (p[i])) {
                c = p[i];
                printf ("%c",  c);
            }
            if (ispunct (p[i])) {
                c = p[i];
                printf ("%c",  c);
            }
            
            if (isblank (p[i])) {
                c = p[i];
                printf ("%c", c);
            }
            
     }
printf ("\n");
return 0;
}