std::chrono::month:: ok

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chrono I/O
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C-style date and time
std::chrono::month
constexpr bool ok ( ) const noexcept ;
(since C++20)

Checks if the month value stored in * this is in the valid range, i.e., [ 1 , 12 ] .

Return value

true if the month value stored in * this is in the range [ 1 , 12 ] . Otherwise false .

Example

Run this code 
#include <chrono>
#include <iostream>
 
int main()
{
    for (const unsigned mm : {6u, 0u, 16U})
    {
        std::cout << mm << ": ";
        const std::chrono::month m{mm};
        m.ok() ? std::cout << "month is valid\n"
               : std::cout << "month is invalid\n";
    }
}

Output: 

6: month is valid
0: month is invalid
16: month is invalid
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