C++ Character functions

Tags: cpp stl

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:

vector<char> getAllPunctuations () {
    vector<char> ans;
    char ch = numeric_limits<char>::min();
    while (true) {
        // Add current character to answer if it is a punctuation
        if (ispunct(ch)) ans.emplace_back(ch);
        // Keep incrementing ahead
        ch++;
        // Stop loop when it overflows back to starting value
        if (ch == numeric_limits<char>::min()) break;
    }
    return ans;
}

int main () {
    const vector<char> allPuncts = getAllPunctuations();
    for (const char &ch : allPuncts) {
        cout << (int)ch << " " << ch << "\n";
    }
}

Output