C++ std::array::empty

C++ std::array::empty

The std::array::empty function checks whether a std::array is empty. Since std::array has a fixed size determined at compile time, this function always returns false unless the size of the array is explicitly defined as 0. It provides a convenient way to check the emptiness of arrays in a generic programming context.

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Syntax of std::array::empty

constexpr bool empty() const noexcept;

Parameters

The std::array::empty function does not take any parameters.

Return Value

Returns a boolean value:

• true: If the size of the array is 0.
• false: If the size of the array is greater than 0.

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Examples for std::array::empty

Example 1: Checking if a std::array is Empty

This example demonstrates how to use the empty function to check whether a std::array is empty:

#include <iostream>
#include <array>

int main() {
    std::array<int, 0> arr; // Define an array with size 0

    if (arr.empty()) {
        std::cout << "The array is empty." << std::endl;
    } else {
        std::cout << "The array is not empty." << std::endl;
    }

    return 0;
}

Explanation:

1. Define a std::array: An array of size 0 is defined.
2. Use empty(): The empty() function checks whether the size of the array is 0.
3. Output the result: Since the array size is 0, the function returns true, and the output indicates that the array is empty.

Output:

The array is empty.

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Example 2: Using std::array::empty in a Conditional Statement

This example demonstrates checking whether a std::array with non-zero size is empty:

#include <iostream>
#include <array>

int main() {
    std::array<int, 5> arr = {1, 2, 3, 4, 5}; // Define an array with 5 elements

    if (arr.empty()) {
        std::cout << "The array is empty." << std::endl;
    } else {
        std::cout << "The array is not empty." << std::endl;
    }

    return 0;
}

Explanation:

1. Define a std::array: An array with 5 elements is defined and initialized.
2. Use empty(): The empty() function checks whether the array size is 0.
3. Output the result: Since the array size is greater than 0, the function returns false, and the output indicates that the array is not empty.

Output:

The array is not empty.

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Exception Handling in std::array::empty

The std::array::empty function does not throw exceptions as it is marked noexcept. This ensures safe usage when checking if a std::array is empty.