Constexpr
Constexpr is a keyword in C++ that specifies that a variable, function, or object can be evaluated at compile time, enabling compile-time computations and optimizations. It allows developers to perform calculations and initialize data during compilation rather than at runtime, improving performance and enabling advanced metaprogramming techniques. This feature is part of C++'s move toward more expressive compile-time programming, introduced in C++11 and expanded in later standards.
Developers should learn and use constexpr to write more efficient and safer code by shifting computations to compile time, reducing runtime overhead and enabling compile-time validation. It is particularly useful for performance-critical applications, embedded systems, and template metaprogramming, where constant expressions are required for array sizes, template arguments, or const-initialized data. For example, it can be used to compute mathematical constants, validate inputs at compile time, or implement compile-time data structures.