c++ - '转换': is not a member of 'std'

这是我的代码

#include "pch.h"
#include <iostream>
using namespace std;

int main()
{
    // su is the string which is converted to lowercase
    std::wstring su = L"HeLLo WoRld";

    // using transform() function and ::toupper in STL
    std::transform(su.begin(), su.end(), su.begin(), ::tolower);
    std::cout << su << std::endl;
    return 0;
}

它生成以下编译错误。

1>c:\users\root\source\repos\consoleapplication7\consoleapplication7\consoleapplication7.cpp(14): error C2039: 'transform': is not a member of 'std'
1>c:\users\root\source\repos\consoleapplication7\consoleapplication7\consoleapplication7.cpp(14): error C3861: 'transform': identifier not found
1>c:\users\root\source\repos\consoleapplication7\consoleapplication7\consoleapplication7.cpp(15): error C2679: binary '<<': no operator found which takes a right-hand operand of type 'std::wstring' (or there is no acceptable conversion)
1>    0 Warning(s)
1>    3 Error(s)

我在这里做错了什么？

最佳答案

您需要包括标题。

加:

#include <algorithm>