C++ wcsrtombs()

The wcsrtombs() function is defined in <cwchar> header file.

wcsrtombs() prototype

size_t wcsrtombs( char* dest, const wchar_t** src, size_t len, mbstate_t* ps );

The wcsrtombs() function converts the wide character string represented by *src to corresponding multibyte character string and is stored in the character array pointed to by dest if dest is not null. A maximum of len characters are written to dest.

The conversion process is similar to calling wcrtomb() repeatedly. The conversion stops if:

• A wide null character was converted and stored. In this case, src is set to null and ps represents initial shift state.
• An invalid wide character was encountered. In this case, src is set to point the beginning of the first unconverted wide character.
• len bytes has been stored in dest. In this case, src is set to point the beginning of the first unconverted wide character.

wcsrtombs() Parameters

• >dest: Pointer to the character array where the converted multibyte character is stored.
• src: Pointer to pointer to the first wide character to convert.
• len: Maximum number of bytes available in dest array.
• ps: Pointer to the conversion state object.

wcsrtombs() Return value

• On success, the wcsrtombs() function returns the number of multibyte characters written to dest excluding the terminating wide null character but including shift sequences.
  If dest is a null pointer, it returns the number of wide characters that would have been written excluding the terminating null character.
• On conversion error, -1 is returned and errno is set to EILSEQ.

Example: How wcsrtombs() function works?

#include <cwchar>
#include <clocale>
#include <iostream>
using namespace std;

int main()
{
	setlocale(LC_ALL, "en_US.utf8");
	
	const wchar_t* wstr = L"\u0763\u0757\u077f\u075f";
	char str[20];
	mbstate_t ps = mbstate_t();
	
	int len = 10;
	int retVal;
	
	retVal = wcsrtombs(str, &wstr, len, &ps);
	cout << "Number of multibyte characters written (excluding \"\\0\") = " << retVal << endl;
	cout << "Multibyte character = " << str << endl;
	
	return 0;
}

When you run the program, the output will be:

Number of multibyte characters written (excluding "\0") = 8
Multibyte character = ݣݗݿݟ