# std::chrono::day::ok

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< cpp‎ | chrono‎ | day

constexpr bool ok() const noexcept; |  | (since C++20)

Checks if the day value stored in *this is in the valid range, i.e., [1, 31].

### Return value

true if the day value stored in *this is in the range [1, 31]. Otherwise false.

### Example

Run this code

    #include <iostream>
    #include <chrono>

    int main()
    {
        std::chrono::day d1{15};
        std::cout << static_cast<unsigned>(d1);
        if (d1.ok()) {
            std::cout << " is a valid day.\n";
        } else {
            std::cout << " is an invalid day!\n";
        }

        std::chrono::day d2{35};
        std::cout << static_cast<unsigned>(d2)
                  << (d2.ok() ? " is a valid day.\n"
                              : " is an invalid day!\n");
    }

Output:

    15 is a valid day.
    35 is an invalid day!

### See also

operator unsigned | retrieves the stored day value (public member function)

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