Mutable
Example
cpp
#include <iostream>
class A {
public:
int a;
mutable int b;
void change() const
{
b = 10; // this is allowed because b is mutable
}
};
int main()
{
A a;
a.a = 5;
a.b = 5;
std::cout << a.a << std::endl;
std::cout << a.b << std::endl;
a.change();
std::cout << a.a << std::endl;
std::cout << a.b << std::endl;
}Explanation
mutable is a keyword that allows you to change a variable in a const function.