Calculate age from DateTime?

Question

Calculate age from DateTime?

Jassim Al Rahma 1,616

Hi,

I am trying:

int age = DateTime.Today.Subtract(DXDateOfBirth.Date);

but getting this error:

Argument 1: cannot convert from 'System.DateTime?' to 'System.DateTime'

Kindly help..

Thanks,
Jassim

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Answer 1

Michael Taylor 60,161

DXDateOfBirth.Date is typed as DateTime? or a nullable datetime. If you are sure this is always a valid date then use the .GetValueOrDefault() method.

   int age = DateTime.Today.Subtract(DXDateOfBirth.Date.GetValueOrDefault());

If you might not actually have a date then you should first check to see if it is set.

   int age = DXDateOfBirth.Date.HasValue ? DateTime.Today.Subtract(DXDateOfBirth.Date.Value) : 0;

Jassim Al Rahma 1,616 Reputation points

2022-12-27T14:27:40.597+00:00
I tried this:

int age = DXDateOfBirth.Date.HasValue ? DateTime.Today.Subtract(DXDateOfBirth.Date.Value) : 0;

but getting:

Cannot implicitly convert type 'System.TimeSpan' to 'int' (CS0029)
Michael Taylor 60,161 Reputation points

2022-12-27T16:55:17.39+00:00
Subtracting dates yields a TimeSpan. That would be the type of age. If you want an integral value then you need to identify what that numeric value represents. Days? Then use TotalDays.

int days = DXDateOfBirth.Date.HasValue ? DateTime.Today.Subtract(DXDateOfBirth.Date.Value).TotalDays : 0

If you want years then TimeSpan won't work as it only goes to days. In this case you should just subtract the Years from the DateTime values directly.

int years = DXDateOfBirth.Date.HasValue ? (DateTime.Today.Years - DXDateOfBirth.Date.Value.Years) : 0;

Answer 2

Here is something to try adapted from this code.

public static class Extensions  
{  
    public static int Age(this DateTime? sender)  
    {  
        if (sender.HasValue)  
        {  
            var today = DateTime.Today;  
            var age = today.Year - sender.Value.Year;  
            if (sender.Value.Date > today.AddYears(-age)) age--;  
            return age;  
        }  
        else  
        {  
            return 0;  
        }  
    }  
}

In a console project

static void Main(string[] args)  
{  
    DateTime? birthdate = new DateTime(1956, 9, 24);  
    Console.WriteLine(birthdate.Age());  
    Console.ReadLine();  
}

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Calculate age from DateTime?

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