What do u meant by 'mutant' key word?

Question

How does this mutant key word works?

Answer 1

I think you meant 'mutable'.
Read the following:
class one {
private:
mutable int count=0;

public:
void print() const {
std::cout<<"Hello world";
++count; //would give an error if it weren't mutable
}
};

The method print() is marked const,so it can't modify data members of that class. Now,let's say you want to know how many times a user called print(),how would you do it. You use the keyword mutable when you declare the counter variable,thus you can modify it within const methods of a class.