Full prototype:
int isupper(int);
Purpose and Notes:
Tests whether the argument passed into the function is a locale-specific upper-case alphabetical character.
Returns:
int- C-style true or false dpending on if the character passed in was uppercase or not according to the set locale.
Argument 1:
int- A character passed in (including EOF, hence int instead of char) to be tested on whether or not it is a uppercase alphabetical character according to the set-locale.