DateTime.CompareTo() Method in C#

This method is used to compare the value of this instance to a specified DateTime value and indicates whether this instance is earlier than, the same as, or later than the specified DateTime value. There are two methods in the overload list of this method as follows:

• CompareTo(DateTime)
• CompareTo(Object)

CompareTo(DateTime) Method

This method is used to compare the value of this instance to a specified DateTime value and returns an integer that indicates whether this instance is earlier than, the same as, or later than the specified DateTime value. Syntax:

public int CompareTo (DateTime value);

Here, the parameter value is the object to compare to the current instance. Return Value: This method return a signed number indicating the relative values of this instance and the value parameter.

• Less than zero : If this instance is earlier than value.
• Zero : If this instance is the same as value.
• Greater than zero : If this instance is later than value.

Example: csharp

// C# code to demonstrate
// CompareTo(DateTime) function
using System;

public class GFG {

    // Main Method
    public static void Main()
    {

        // Taking two DateTime Objects
        DateTime d1 = new DateTime(2018, 12,
                              31, 16, 0, 0);

        DateTime d2 = new DateTime(2018, 12,
                              31, 20, 0, 0);

        // Using the method
        int res = d1.CompareTo(d2);

        string r;

        if (res > 0)
            r = "is later than";

        else if (res == 0)
            r = "is the same time as";
        else
            r = "is earlier than";

        Console.WriteLine("{0} {1} {2}", d1, r, d2);
    }
}

CompareTo(Object) Method

This method is used to compare the value of this instance to a specified object that contains a specified DateTime value and returns an integer that indicates whether this instance is earlier than, the same as, or later than the specified DateTime value. Syntax:

public int CompareTo (object value);

Here, the parameter value is the boxed object to compare, or null. Return Value: This method return a signed number indicating the relative values of this instance and the value parameter.

• Less than zero : If this instance is earlier than value.
• Zero : If this instance is the same as value.
• Greater than zero : If this instance is later than value.

Exception: This method will give ArgumentException if the value is not a DateTime. Example: csharp

// C# code to demonstrate
// CompareTo(Object) function
using System;

public class GFG {

    // Main Method
    public static void Main()
    {

        // Taking a DateTime Object
        DateTime d1 = new DateTime(2018, 12,
                              31, 16, 0, 0);
                              
        // Using the method
        // Here, "DateTime.Today" is
        // the property of DateTime struct
        int res = d1.CompareTo(DateTime.Today);

        string r;

        if (res > 0)
            r = "is later than";

        else if (res == 0)
            r = "is the same time as";
        else
            r = "is earlier than";

        Console.WriteLine("{0} {1} {2}", d1, r, 
                                DateTime.Today);
    }
}

Output:

12/31/2018 16:00:00 is earlier than 01/21/2019 00:00:00

Reference:

• https://docs.microsoft.com/en-us/dotnet/api/system.datetime.compareto?view=netframework-4.7.2