Using the const and constexpr qualifiers

In this section, we will add the const and constexpr qualifiers to variables, and discuss how they can be added to functions in both their input parameters and as return values. These qualifiers will be used quite liberally as we move forward in the C++ language. The use of const and constexpr can enable values to be initialized, yet never again modified. Functions can advertise that they will not modify their input parameters, or that their return value may only be captured (but not modified) by using const or constexpr. These qualifiers help make C++ a more secure language. Let’s take a look at const and constexpr in action.

const and constexpr variables

A const qualified variable is a variable that must be initialized, and may never be assigned a new value. It is seemingly a paradox to pair the usage of const and a variable together – const implies not to change, yet the concept of a variable is to inherently hold different...