When should a member function have a const qualifier and when shouldn't it?

Question

About six years ago, a software engineer named Harri Porten wrote this article, asking the question, \"When should a member function have a const qualifier and when shouldn\'t i

Answer 1

Here are some good articles:
Herb Sutter's GotW #6
Herb Sutter & const for optimizations
More advice on const correctness
From Wikipedia

I use const method qualifiers when the method does not alter the class' data members or its common intent is not to modify the data members. One example involves RAII for a getter method that may have to initialize a data members (such as retrieve from a database). In this example, the method only modifies the data member(s) once during initialization; all other times it is constant.

I'm allowing the compiler to catch const errors during compile time rather than me catching them during run-time (or a User).