Application of if constexpr

The if constexpr is mainly used where decisions need to be made at compile time based on type traits or other constant expressions. Here are some key applications:

• Template Metaprogramming: template metaprogramming can be used to create general templets as it have abilities to adapt behaviour based on conditions of compile time.
• Conditional Code Generation: It can be used to include or exclude sections of code based on certain conditions during the compilation process.
• Compile-Time Assertions: checking conditions using if constexpr during the process compilation of the program helps users to identify errors early and ensure that specific conditions are met at compile time.
• Algorithm Optimization: It helps for the selection of optimized algorithms at compile time resulting optimizing performance without any runtime cost.

In C++17, if constexpr feature was introduced to allow compile-time branching based on constant expressions. Unlike regular if statements, which are evaluated at runtime, the if constexpr allows the compiler to discard branches of code that do not apply. It means only the branch of code for which the condition is true is compiled and other code branch is discarded during compilation.