[c++] Constexpr member functions

In C++, a constexpr member function is a member function of a class that can be evaluated at compile time. Using constexpr member functions allows the computation of values to occur at compile time, which can improve performance and efficiency.



Here’s the syntax for defining a constexpr member function in a C++ class:

class MyClass {
    constexpr int compute() const {
        // code to compute and return a value

In this example, the compute member function is declared as constexpr, allowing it to be evaluated at compile time.


Using constexpr member functions offers several benefits:


class Circle {
    constexpr Circle(double radius) : radius(radius) {}

    constexpr double area() const {
        return 3.14159 * radius * radius;

    double radius;

int main() {
    constexpr Circle c(5.0);
    constexpr double circleArea = c.area();
    // 'circleArea' is computed at compile time
    return 0;

In this example, the area member function of the Circle class is declared as constexpr, allowing the computation of the circle’s area to occur at compile time.