C++ 20 (2a) New Features - constexpr Extensions

The video tutorial covers the use of constant eval and constant init keywords in C++. It explains how static duration variables are initialized before the main function and the potential issues with static order initialization. The tutorial demonstrates how to use constexpr to ensure compile-time initialization and execution of functions. It also introduces the coneval keyword, which forces functions to execute at compile time, and discusses handling runtime parameters with constexpr. The video concludes with practical examples and solutions to common compilation issues.

What is the primary purpose of using the constant init keyword in C++20?

• To enable dynamic memory allocation

• To allow variables to be modified after initialization

• To prevent static order initialization issues

• To ensure variables are initialized at runtime

How can you ensure a variable is initialized at compile time?

• By initializing it in the main function

• By using a constexpr function

• By declaring it as static

• By using a runtime function

Why does a constexpr function sometimes execute at runtime?

• Because it depends on the compiler's optimization

• Because it is always executed at runtime

• Because it can be executed at either compile time or runtime

• Because it requires user input to determine execution time

What happens when a consteval function uses a runtime parameter?

• The function executes successfully

• The function cannot compile

• The function executes at runtime

• The function is ignored by the compiler

What is a key characteristic of a consteval function?

• It appears in the symbol table

• It generates binary code

• It can be debugged easily

• It is executed at compile time only