Using DateOnly and Record's is C# to work out how old someone is

DateOnly.HowOldIsPerson.cs

using System;

Console.WriteLine("No static void main");

var p = new Person(Guid.NewGuid(), "John", new DateOnly(1975, 1, 1));
Console.WriteLine(p.ToString());

public record Person(Guid Id, string Name, DateOnly DateOfBirth)
{
    public override string ToString()
    {
        var currentDate = DateOnly.FromDateTime(DateTime.Today);
        var age = currentDate.Year - DateOfBirth.Year;
        var months = currentDate.Month - DateOfBirth.Month;
        if (currentDate.Day < DateOfBirth.Day)
            months--;

        if (months < 0)
        {
            age--;
            months += 12;
        }

        return $"{Name} is {age} years and {months} months old";
    }
}