C++ Character functions

Following functions are a part of the <cctype> header file

Checking character class

Note: true is 1 and false is 0 in these functions

• isalpha(char c) : Returns true if c is a-z or A-Z
• isupper(char c) : Returns true if c is A-Z i.e. UPPERCASE
• islower(char c) : Returns true if c is A-Z i.e. lowercase
• isdigit(char c) : Returns true if c is 0-9
• isxdigit(char c) : Returns true if c is hexadecimal digit (0-9 or a-f)
• isalnum(char c) : Returns true if c is alphanumeric (a-z or A-Z or 0-9)
• isblank(char c) : Returns true if c is a space or tab
• ispunct(char c) : Returns true if c is a punctuation mark
• isprint(char c) : Returns true if c is printable on console

Changing case

• tolower(char c) - returns lowercase equivalent of input character.
• toupper(char c) - returns UPPERCASE equivalent of input character.

Code to print ALL punctuation characters:

char c = numeric_limits<char>::min();
while (true)
{
    if (ispunct(c)) {
        cout << c << " ";
    }
    c++;
    // Stop when it overflows back to starting value
    if (c == numeric_limits<char>::min()) {
        break;
    }
}
cout << endl;

Output:

! " # $ % & ' ( ) * + , - . / : ; < = > ? @ [ \ ] ^ _ ` { | } ~