# std::wcsspn

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< cpp‎ | string‎ | wide

Defined in header `<cwchar>` |  |
size_t wcsspn( const wchar_t* dest, const wchar_t* src ); |  |

Returns the length of the maximum initial segment of the wide string pointed to by dest, that consists of only the characters found in wide string pointed to by src.

### Parameters

dest | - | pointer to the null-terminated wide string to be analyzed
src | - | pointer to the null-terminated wide string that contains the characters to search for

### Return value

The length of the maximum initial segment that contains only characters from wide string pointed to by src.

### Example

Run this code

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

    int main()
    {
        wchar_t dest[] = L"白猫 黑狗 甲虫";
        const wchar_t src[] = L" 狗猫 白黑 ";
        const std::size_t len = std::wcsspn(dest, src);
        dest[len] = L'\0'; // terminates the segment to print it out

        std::wcout.imbue(std::locale("en_US.utf8"));
        std::wcout << L"The length of maximum initial segment is " << len << L".\n";
        std::wcout << L"The segment is \"" << dest << L"\".\n";
    }

Possible output:

    The length of maximum initial segment is 6.
    The segment is "白猫 黑狗 ".

### See also

wcscspn | returns the length of the maximum initial segment that consists of only the wide not found in another wide string (function)
wcspbrk | finds the first location of any wide character in one wide string, in another wide string (function)

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