Predefined Character Functions

1. The header file cctype contains definitions of many predefined functions that deal with characters.
   
   
2. The function isspace returns true if its argument is a whitespace character, otherwise it returns false. Whitespace characters are characters that are displayed as blank spaces on the screen. C++ has 3 whitespace characters: the blank character, the tab character, and the new-line character.
   
   
3. The function toupper returns the integer value of the character that is the upper case of its argument, if the argument is a lower case letter. It returns the argument unchanged if the argument is not a lower case letter.