比较 C++ 中的结构时找不到 == 运算符

2021-12-23 00:00:00 struct comparison-operators c++

比较以下结构的两个实例，我收到一个错误:

Comparing two instances of the following struct, I receive an error:

struct MyStruct1 {
    MyStruct1(const MyStruct2 &_my_struct_2, const int _an_int = -1) :
        my_struct_2(_my_struct_2),
        an_int(_an_int)
    {}

    std::string toString() const;

    MyStruct2 my_struct_2;
    int an_int;
};

错误是:

错误 C2678:二进制==":无运算符found 需要一个左操作数'myproj::MyStruct1' 类型(或那里是不可接受的转换)

error C2678: binary '==' : no operator found which takes a left-hand operand of type 'myproj::MyStruct1' (or there is no acceptable conversion)

为什么?

推荐答案

在 C++ 中，struct 没有默认生成的比较运算符.你需要自己写:

In C++, structs do not have a comparison operator generated by default. You need to write your own:

bool operator==(const MyStruct1& lhs, const MyStruct1& rhs)
{
    return /* your comparison code goes here */
}

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