No == operator found while comparing structs in C++

Question

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;
};

The error is:

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

Why?

Answer 1

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 */
}