NAME

std::fgetws - std::fgetws

Synopsis

Defined in header <cwchar>
wchar_t* fgetws( wchar_t* str, int count, std::FILE* stream );

Reads at most count - 1 wide characters from the given file stream and stores them
in str. The produced wide string is always null-terminated. Parsing stops if
end-of-file occurs or a newline wide character is found, in which case str will
contain that wide newline character.

Parameters

str - wide string to read the characters to
count - the length of str
stream - file stream to read the data from

Return value

str on success, a null pointer on an error.

Example

// Run this code

#include <array>
#include <clocale>
#include <cstdio>
#include <cstdlib>
#include <cwchar>
#include <cwctype>
#include <iomanip>
#include <iostream>
#include <span>
#include <string>

void dump(std::span<const wchar_t> sp, std::size_t width = 14)
{
for (wchar_t wc : sp)
std::wcout << (std::iswprint(wc) ? wc : L'.');
std::wcout << std::wstring(width > sp.size() ? width - sp.size() : 1, L' ')
<< std::hex << std::uppercase << std::setfill(L'0');
for (wchar_t wc : sp)
std::wcout << std::setw(sizeof wc) << static_cast<unsigned>(wc) << ' ';
std::wcout << '\n';
}

int main()
{
// Create temp file that contains wide characters
std::setlocale(LC_ALL, "en_US.utf8");
std::FILE* tmpf = std::tmpfile();

for (const wchar_t* text : {
L"Tétraèdre" L"\n",
L"Cube" L"\n",
L"Octaèdre" L"\n",
L"Icosaèdre" L"\n",
L"Dodécaèdre" L"\n"
})
if (int rc = std::fputws(text, tmpf); rc == EOF)
{
std::perror("fputws()"); // POSIX requires that errno is set
return EXIT_FAILURE;
}

std::rewind(tmpf);

std::array<wchar_t, 12> buf;
while (std::fgetws(buf.data(), buf.size(), tmpf) != nullptr)
dump(std::span(buf.data(), buf.size()));

return EXIT_SUCCESS;
}

Possible output: