/**
 * pset 2
 * Vigenere's Cipher
 *
 * Mike
 *
 * Scrambles a message by k characters
 */

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

int main(int argc, string argv[])

// get valid input

{
    while(argc != 2)
{
    printf("error\n");
    return 1;
}

// convert input into key

    string scramble = GetString();
    int i;
    for (i = 0; i < strlen(scramble); i++)
    if isalpha(scramble[i])
    {
        int k = toupper(argv[1][i]);
        int key = (k - 64);

// print character up/low

        if(isupper(scramble[i]))
        {
            int code = (scramble[i] - 65 + key) %26;
            printf("%c", (char) code + 65);
        }

//lowercase

        else if(islower(scramble[i]))
        {
            int code = (scramble[i] - 97 + key) %26;
            printf("%c", (char) code + 97);
        }
        else (printf("%c", scramble[i]));
    }
    else (printf("%c", scramble[i]));
    printf("\n");
}