How to Create a Constexpr Array from 0 to N in C 11?

Crafting a Constexpr Array Spanning from 0 to N in C 11

In the realm of modern C programming, the concept of constexpr arrays has gained significant attention for its unparalleled efficiency and compile-time evaluation capabilities. Amidst this innovation, a question arises: how can one construct a constexpr array ranging from 0 to n in C 11?

The key to this challenge lies in the powerful combination of constexpr constructors and iterative initialization. Let's break down the essence of this approach:

#include <iostream>

template<int N>
struct A {
    constexpr A() : arr() {
        for (auto i = 0; i != N; ++i)
            arr[i] = i;
    }
    int arr[N];
};

int main() {
    constexpr auto a = A<4>();
    for (auto x : a.arr)
        std::cout << x << '\n';
}

Within this code snippet, we define a constexpr constructor within a template structure 'A'. This constructor initializes an integer array 'arr' of size N with elements ranging from 0 to N-1 using a for loop.

By instantiating 'A' as a constexpr object named 'a', we effectively create a constexpr array whose values are computed at compile time. The subsequent loop iterates over this array, printing its elements to the standard output stream.

In summary, by leveraging the versatility of constexpr constructors and iterative initialization, we have crafted a means to construct constexpr arrays ranging from 0 to n in C 11, showcasing the efficiency and compile-time evaluation prowess that this language offers.

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