# wmemmove, wmemmove_s

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< c‎ | string‎ | wide

Defined in header `<wchar.h>` |  |
wchar_t* wmemmove( wchar_t* dest, const wchar_t* src, size_t count ); | (1) | (since C95)
errno_t wmemmove_s( wchar_t *dest, rsize_t destsz, const wchar_t *src, rsize_t count); | (2) | (since C11)

1) 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 `count` is zero, the function does nothing. The arrays may overlap: copying takes place as if the wide characters were copied to a temporary wide character array and then copied from the temporary array to `dest`.
2) Same as (1), except that the following errors are detected at runtime and call the currently installed constraint handler function:

  - `src` or `dest` is a null pointer
  - `destsz` or `count` is greater than RSIZE_MAX/sizeof(wchar_t)
  - `count` is greater than `destsz` (overflow would occur)
  As all bounds-checked functions, `wmemmove_s` is only guaranteed to be available if __STDC_LIB_EXT1__ is defined by the implementation and if the user defines __STDC_WANT_LIB_EXT1__ to the integer constant 1 before including `wchar.h`.

### Parameters

dest | - | pointer to the wide character array to copy to
src | - | pointer to the wide character array to copy from
destsz | - | max number of wide characters to write (the size of the destination buffer)
count | - | number of wide characters to copy

### Return value

1) Returns a copy of `dest`
2) Returns zero on success, returns non-zero on error. Also, on error, fills the entire `dst` up to and not including dst+dstsz with null wide characters, L'\0' (unless `dest` is null or `destsz` is greater than RSIZE_MAX/sizeof(wchar_t))

### Notes

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 <stdio.h>
    #include <wchar.h>
    #include <locale.h>

    int main(void)
    {
        setlocale(LC_ALL, "en_US.utf8");

        wchar_t str[] = L"αβγδεζηθικλμνξοπρστυφχψω";
        printf("%ls\n", str);
        wmemmove(str+4, str+3, 3); // copy from [δεζ] to [εζη]
        printf("%ls\n", str);
    }

Output:

    αβγδεζηθικλμνξοπρστυφχψω
    αβγδδεζθικλμνξοπρστυφχψω

### References

- C11 standard (ISO/IEC 9899:2011):

  - 7.29.4.2.4 The wmemmove function (p: 432)

  - K.3.9.2.1.4 The wmemmove_s function (p: 642)

- C99 standard (ISO/IEC 9899:1999):

  - 7.24.4.2.4 The wmemmove function (p: 378)

### See also

memmove memmove_s (C11) | moves one buffer to another (function)
wmemcpy wmemcpy_s (C95)(C11) | copies a certain amount of wide characters between two non-overlapping arrays (function)
C++ documentation for wmemmove

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