Character Classify

Character classification helpers answer questions such as whether a character is a digit or a letter.

character_classify.cpp

#include <cctype>
#include <iostream>

int main() {
    char ch = ;

    bool isDigit = std::isdigit(static_cast<unsigned char>(ch)) != 0;
    bool isAlpha = std::isalpha(static_cast<unsigned char>(ch)) != 0;

    std::cout << "ch=" << ch << std::endl;
    std::cout << "isDigit=" << isDigit << std::endl;
    std::cout << "isAlpha=" << isAlpha << std::endl;
    return 0;
}

#include <cctype>
#include <iostream>

int main() {
    char ch = ;

    bool isDigit = std::isdigit(static_cast<unsigned char>(ch)) != 0;
    bool isAlpha = std::isalpha(static_cast<unsigned char>(ch)) != 0;

    std::cout << "ch=" << ch << std::endl;
    std::cout << "isDigit=" << isDigit << std::endl;
    std::cout << "isAlpha=" << isAlpha << std::endl;
    return 0;
}

#include <cctype>
#include <iostream>

int main() {
    char ch = ;

    bool isDigit = std::isdigit(static_cast<unsigned char>(ch)) != 0;
    bool isAlpha = std::isalpha(static_cast<unsigned char>(ch)) != 0;

    std::cout << "ch=" << ch << std::endl;
    std::cout << "isDigit=" << isDigit << std::endl;
    std::cout << "isAlpha=" << isAlpha << std::endl;
    return 0;
}

isdigit `std::isdigit` reports whether a character represents a digit.

unsigned char cast Casting to `unsigned char` before classification avoids undefined behavior for non-ASCII character values.