warning in-class initialization of non-static data members is incompatible with C++98

This warning indicates that the code is using in-class initialization for non-static data members, which is not supported in C++98. In C++98, non-static data members must be initialized in the constructor.

To resolve this warning, you can either:

1. Upgrade to a newer version of C++ that supports in-class initialization of non-static data members, such as C++11 or later.

2. Initialize non-static data members in the constructor instead of using in-class initialization.

For example, instead of:

class MyClass {
public:
    int myInt = 0; // in-class initialization
};

Use:

class MyClass {
public:
    MyClass() : myInt(0) {} // constructor initialization
private:
    int myInt;
};
``