PSet2 / Substitution

Question

I am trying to make an upper case key and a lower case key of the one typed by the user but when I use the toupper and tolower functions they turn all my chars into lower or upper. Not just the one I want. Valkey is the key the user typed. If they type VBnmdG, I get vbNMDg for all three strings instead of the original untouched, the upper in all uppers and the lower in all lowers.

string key_upper = valkey;
string key_lower = valkey;
for (int i = 0; i < len; i++)
{
    if (isalpha(valkey[i]) == 0)
    {
        printf("Key must only contain alphabetic characters.\n");
        return 1;
    }
    if (isupper(valkey[i]))
    {
        key_lower[i] = tolower(key_lower[i]);
    }
    else if (islower(valkey[i]))
    {
        key_upper[i] = toupper(key_upper[i]);
    }
    else
        continue;
}

printf("valkey: %s\n", valkey);
printf("keyupper: %s\n", key_upper);
printf("keylower: %s\n", key_lower);

Answer 1

Your problem is what you exactly told the program to do, you said if it is a lowercase char you turn it into uppercase and vice versa.

Also your else statement and continue can be omitted since you're not really doing anything after those making it useless.

Answer 2

I was declaring the variables where I wanted to store de upper and lower keys by copying the inserted key. All three variables were using the same memory space and overwrote each other. I changed:

string key_upper = valkey;

string key_lower = valkey;

and instead I put this to declare the variables:

char key_upper[26];

char key_lower[26];

and it worked!