C++ “const” keyword explanation

Question

When reading tutorials and code written in C++, I often stumble over the const keyword.

I see that it is used like the following:

const          


        

Answer 1

This:

void myfunc( const char x );

means you you cannot change x inside the function, i.e. this is illegal:

void myfunc( const char x ) {
    x = ...;
}

while:

int myfunc() const;

only makes sense if myfunc() is a method inside a class; it basically means the method cannot modify the class instance (i.e. the state of the instance before and after calling instance.myfunc() will be the same).