vigenere set key values not working

Question

This is the code I am using to change the string key into their respective shift values. For some reason as I have put a printf to test this, it outputs some weird strings of numbers.

int k[strlen(c)];
    for(int i = 0; i < strlen(c); i++)
    {
        if(islower(k[i]))
            k[i] = c[i] - 'a';
        else
            k[i] = c[i] - 'A';
        printf("%i", k[i]);
    }

c is equal to argv[1]

Answer 1

I think the mistake lies in the "if condition" in your for loop. The condition is islower(k[i]), which is seems to be wrong because the array is not initialised and must be containing some garbage values.

Instead, it should be replaced by islower(c[i]).(Afterall, the keyword is stored in c[] and not k[]).

Though, I am assuming that you verified the keyword to be valid.