std:: ispunct

Checks if the given character is a punctuation character as classified by the current C locale. The default C locale classifies the characters ( !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~ ) as punctuation.

The behavior is undefined if the value of ch is not representable as unsigned char and is not equal to EOF .

Parameters

Return value

Non-zero value if the character is a punctuation character, zero otherwise.

Notes

Like all other functions from <cctype> , the behavior of std::ispunct is undefined if the argument's value is neither representable as unsigned char nor equal to EOF . To use these functions safely with plain char s (or signed char s), the argument should first be converted to unsigned char :

bool my_ispunct(char ch)
{
    return std::ispunct(static_cast<unsigned char>(ch));
}

Similarly, they should not be directly used with standard algorithms when the iterator's value type is char or signed char . Instead, convert the value to unsigned char first:

int count_puncts(const std::string& s)
{
    return std::count_if(s.begin(), s.end(),
                      // static_cast<int(*)(int)>(std::ispunct)         // wrong
                      // [](int c){ return std::ispunct(c); }           // wrong
                      // [](char c){ return std::ispunct(c); }          // wrong
                         [](unsigned char c){ return std::ispunct(c); } // correct
                        );
}

Example

#include <cctype>
#include <clocale>
#include <iostream>
 
int main()
{
    unsigned char c = '\xd7'; // the character × (multiplication sign) in ISO-8859-1
 
    std::cout << "ispunct(\'\\xd7\', default C locale) returned "
              << std::boolalpha << (bool)std::ispunct(c) << '\n';
 
    std::setlocale(LC_ALL, "en_GB.iso88591");
    std::cout << "ispunct(\'\\xd7\', ISO-8859-1 locale) returned "
              << std::boolalpha << (bool)std::ispunct(c) << '\n';
}

ispunct('\xd7', default C locale) returned false
ispunct('\xd7', ISO-8859-1 locale) returned true

See also