Vigenere BaZ key frustration

Question

I have gone through many of the stack and reddit questions concerning the Vigenere problem. I am so close to figuring it out I can taste it!

I have been working through the issue of the BaZ key for the last few hours and am ready to pull my hair out. My cs50 check returns:

:( encrypts "BaRFoo" as "CaQGon" using "BaZ" as keyword

\ expected output, but not "CBzSREpon\n"

I have checked for the key being upper and lower case, and have been through everything as logically as I can. At this point, I've been staring at my screen for too long and am missing something.

This is my code:

for (i = 0, l = strlen(p); i < l; i++)
{
    if (isalpha(p[i]))
    {
        if (isupper(p[i]) && isupper(k[n]))
        {
            int c = (p[i] - 65 + ((k[n]) - 65)) % 26;
            printf("%c", c + 65);
            n++;
        }
        if (isupper(p[i]) && islower(k[n]))
        {
            int c = (p[i] - 65 + (k[n] - 97)) % 26;
            printf("%c", c + 65);
            n++;
        }
        if (islower(p[i]) && islower(k[n]))
        {
            int c = (p[i] - 97 + (k[n] - 97)) % 26;
            printf("%c", c + 97);
            n++;
        }
        if (islower(p[i]) && isupper(k[n]))
        {
            int c = (p[i] - 97 + ((k[n]) - 65)) % 26;
            printf("%c", c + 97);
            n++;
        }
        if (n == g)
            n = 0;
    }
    if (!isalpha(p[i]))
    {
        printf("%c", p[i]);
    }
}
printf("\n");

return 0;

What am I missing? Someone please help me out before I go bald!

Answer 1

You are giving more than one output for one letter. You have to use "else if" after first "if"s. Or make that n++ at the end of the first big if block. Incrementing n at the first internal if block may cause it enters second if block too because k[n] changes.