I need to be able to convert case in strings, so that "Hello" becomes "hello". Ultimately, I need to compare them.

How would I convert:

char *string = "HEllO";

to the string "hello"?

• c
• ascii

First, your string is not declared properly, it should be:

char *string = "Hello";

Now, to convert to lowercase, try this:

char *lowercase(const char *str)
{
    int length = strlen(str);
    char *dup = malloc(length + 1);
    strcpy(dup, str);

    for (int i = 0; i < length; i++)
    {
         dup[i] = tolower(dup[i]);
    }

    return dup; // remember to free when done!
}

Simply perform this inline.

   char string[] = "Hello";
   char * ptr;

   for (ptr = string; *ptr != '\0'; ++ptr)
   {
       *ptr = tolower(*ptr);
   }