std::wctob (3) Linux Manual Page

std::wctob – std::wctob

Synopsis

Defined in header<cwchar>

    int wctob(std::wint_t c);

Narrows a wide character c if its multibyte character equivalent in the initial shift state is a single byte.
This is typically possible for the characters from the ASCII character set, since most multibyte encodings (such as UTF-8) use single bytes to encode those characters.

Parameters

c – wide character to narrow

Return value

EOF if c does not represent a multibyte character with length 1 in initial shift state.
Otherwise, the single-byte representation of c as unsigned char converted to int

Example

// Run this code

#include <clocale>

#include <cwchar>

#include <iostream>
void try_narrowing(wchar_t c)

{
    int cn = std::wctob(c);
    if (cn != EOF)
        std::cout << '\'' << c << "' narrowed to " << +cn << '\n';
    else
        std::cout << '\'' << c << "' could not be narrowed\n";
}
int main()

{
    std::setlocale(LC_ALL, "th_TH.utf8");
    std::cout << std::hex << std::showbase << "In Thai UTF-8 locale:\n";
    try_narrowing(L'a');
    try_narrowing(L'๛');
    std::setlocale(LC_ALL, "th_TH.tis620");
    std::cout << "In Thai TIS-620 locale:\n";
    try_narrowing(L'a');
    try_narrowing(L'๛');
}

Output:

  In Thai UTF-8 locale:
  ‘0x61’ narrowed to 0x61
  ‘0xe5b’ could not be narrowed
  In Thai TIS-620 locale:
  ‘0x61’ narrowed to 0x61
  ‘0xe5b’ narrowed to 0xfb

See also

       widens a single-byte narrow character to wide character, if possible
btowc (function)
       narrows characters
narrow (public member function of std::basic_ios<CharT,Traits>)
       invokes do_narrow
narrow (public member function of std::ctype<CharT>)