How to fix Vigenere

Question

I inputted Bill Carroll with the key 'key' and got BBBBBBBBBBiii. I can't seem to figure out what I am doing wrong. My code is as follows.

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

int main(int argc, string argv[])
{
    // checks usage
    if (argc != 2)
    {
        printf("\nUsage: ./vigenere <key>\n\n");
        return 1;
    }
    else
    {
        int key = atoi(argv[1]);

[EDIT: remaining, irrelevant code removed for Honor Code compliance.]

Answer 1

The program calls for entry of a text string for the key. Your code, probably cut and pasted from the previous part of the exercise, attempts to convert argv[1] to an integer. Since argv[1] is a string, it causes seg faults later.

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