Comparing using CompareTo C# Method


A colleague asked me for a suggestion on the program module he is doing that involves determining if one value is “>” greater than, “=” equal or “<” less than another value. I first thought of a solution involving a stack but its too low level and involves much longer code. After some suggestions and trying to think of another way, he came across of a solution to use CompareTo C# method.

What is CompareTo C# Method?

First, MSDN defines IComparable as an interface that “Defines a generalized type-specific comparison method that a value type or class implements to order or sort its instances.” It has a method called CompareTo which as defined by MSDN “Compares the current instance with another object of the same type and returns an integer that indicates whether the current instance precedes, follows, or occurs in the same position in the sort order as the other object.”

The CompareTo method is available on all objects as long as the objects has the same type. See the sample code below for comparing value types integer and a string type.



The Return Value of CompareTo

The CompareTo method has a return value of int. The integer value return will be one of the values less than 0, 0 or greater than zero as what is shown below.



Nullable Types Does Not Implement CompareTo

Take note that Nullable types like int? short for Nullable<int> does not implement the CompareTo method. It will not even compile since the method is not implemented.


This blog post will serve as a quick reference for me whenever there is a need for me to use sorting or comparison of data when programming. I hope it will serve the same for you.




  1. pranil says:

    Hello.. i want how the values will get sorted using compareTo() Method.
    for e.g. 30,20,25,40. can please tell me step by step excution using compareTo() method. Please reply as soon as possible.

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