std::wmemcpy

C++

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Concepts library (C++20)

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Technical Specifications

Strings library

Null-terminated strings

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Wide strings

Classes

basic_string

basic_string_view (C++17)

char_traits

Null-terminated wide strings

Functions
Character manipulation
iswalnum iswalpha iswlower iswupper iswdigit iswxdigit iswblank (C++11) wctype iswctype	iswcntrl iswgraph iswspace iswprint iswpunct towlower towupper wctrans towctrans
Conversions to numeric formats
wcstolwcstoll (C++11) wcstoulwcstoull (C++11)	wcstofwcstodwcstold (C++11)(C++11) wcstoimaxwcstouimax (C++11)(C++11)
String manipulation
wcslen wcscpy wcsncpy wcscat wcsncat wcscmp wcscoll wcsncmp	wcsxfrm wcschr wcsrchr wcspbrk wcsspn wcscspn wcsstr wcstok
Array manipulation
wmemcpy
wmemmove
wmemcmp
wmemchr
wmemset

Defined in header <cwchar>
wchar_t* wmemcpy( wchar_t* dest, const wchar_t* src, std::size_t count );

Copies exactly count successive wide characters from the wide character array pointed to by src to the wide character array pointed to by dest. If the objects overlap, the behavior is undefined. If count is zero, the function does nothing.

Parameters

dest	-	pointer to the wide character array to copy to
src	-	pointer to the wide character array to copy from
count	-	number of wide characters to copy

Return value

dest

Notes

This function's analog for byte strings is std::strncpy, not std::strcpy.

This function is not locale-sensitive and pays no attention to the values of the wchar_t objects it copies: nulls as well as invalid characters are copied too.

Example

Run this code

#include <iostream>
#include <cwchar>
#include <clocale>
#include <locale>

int main(void)
{
    wchar_t from1[] = L"";
    const size_t sz1 = sizeof from1 / sizeof *from1;
    wchar_t from2[] = L"";
    const size_t sz2 = sizeof from2 / sizeof *from2;
    wchar_t to[sz1 + sz2];

    std::wmemcpy(to, from1, sz1); // copy from1, along with its null terminator
    std::wmemcpy(to + sz1, from2, sz2); // append from2, along with its null terminator

    std::setlocale(LC_ALL, "en_US.utf8");
    std::cout.imbue(std::locale("en_US.utf8"));
    std::wcout << "Wide array contains: ";
    for(size_t n = 0; n < sizeof to / sizeof *to; ++n)
        if(to[n])
            std::wcout << to[n];
        else
            std::wcout << "\\0";
    std::wcout << '\n';
}

Possible output:

Wide array contains: \0\0

See also

strncpy	copies a certain amount of characters from one string to another (function)
wmemmove	copies a certain amount of wide characters between two, possibly overlapping, arrays (function)