Full prototype:
int toupper(int);
Purpose and Notes:
Takes the argument passed into the function and converts it to its locale-specific corresponding upper-case character if applicable and returns the result.
If the character passed in does not have a corresponding locale-specific uppercase or is already uppercase then it is simply returned "as-is".
Returns:
int- the corresponding locale-specific uppercase character of the argument passed in, or simply the character passed in as the only argument if it does not have a corresponding uppercase character.
Argument 1:
int- the character that is to be evaluated to produce its locale-specific corresponding uppercase character.