std::wctob

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Technical Specifications

 

Strings library

Null-terminated strings

Byte strings

Multibyte strings

Wide strings

Classes

basic_string

char_traits

 

Null-terminated multibyte strings

Wide/multibyte conversions
mbsinit
mbtowc mbstowcs btowc mbrtowc mbsrtowcs mbrtoc16 (C++11) mbrtoc32 (C++11) mblen	wctomb wcstombs wctob wcrtomb wcsrtombs c16rtomb (C++11) c32rtomb (C++11) mbrlen
Types
mbstate_t

 

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

btowc	widens a single-byte narrow character to wide character, if possible (function)
narrow	narrows characters (public member function of std::basic_ios)
narrow	invokes do_narrow (public member function of std::ctype)
C documentation for wctob