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The const keyword specifies that a variable's value is constant and tells the compiler to prevent the programmer from modifying it. In C, constant values default to external linkage, so they can appear only in source files.
The const keyword allows you to specify whether or not a variable is modifiable. You can use const to prevent modifications to variables and const pointers and const references prevent changing the data pointed to (or referenced).
Const (constant) in programming is a keyword that defines a variable or pointer as unchangeable. A const may be applied in an object declaration to indicate that the object, unlike a standard variable, does not change. Such fixed values for objects are often termed literals.
Constants are block-scoped, much like variables declared using the let keyword. The value of a constant can't be changed through reassignment (i.e. by using the assignment operator), and it can't be redeclared (i.e. through a variable declaration).
On a blog on the progress of C++17 I read the following:
P0007proposes a helper function templateas_const, which simply takes a reference and returns it as a reference toconst.template <typename T> std::add_const_t<T>& as_const(T& t) { return t } template <typename T> void as_const(T const&&) = delete;
Why is the const&& overload deleted?
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