C# | Char.CompareTo() Method

In C#, Char.CompareTo() is a System.Char struct method which is used to compare this instance of a specified object or value type and check whether the given instance is precedes, follow, or appears in the same position in the sort order as the specified object or value type. This method can be overloaded by passing the different type of arguments to it.

• Char.CompareTo(Char) Method
• Char.CompareTo(Object) Method
  

Char.CompareTo(Char) Method

This method is used to compare this instance to a specified Char object and check whether this instance precedes, follows, or appears in the same position in the sort order as the specified Char object. 

Syntax:

public int CompareTo(Char ch);

Parameter:

ch: It is the required Char object which is to be compared.

Return Type: It returns a signed number that shows the position of the instance in the sort order in relation to the ch parameter. The return type of this method is System.Int32. The different cases for the return values are shown in the below table:

Return value	Description
Less than zero	This instance precedes ch.
Zero	This instance has the same position in the sort as in ch.
Greater than zero	This instance follows ch.

Example:

C#

// C# program to demonstrate the
// Char.CompareTo(Char) Method
using System;

class CompareToSample {

    // Main Method
    public static void Main()
    {
        char ch1 = 'Z';
        char ch2 = 'g';
        char ch3 = 'A';

        // using Char.CompareTo(Char) Method
        // returns 0 as this instance has
        // same position in the sort as in ch1
        Console.WriteLine('Z'.CompareTo(ch1));

        // using Char.CompareTo(Char) Method
        // returns -13 as this instance
        // precedes ch2
        Console.WriteLine('Z'.CompareTo(ch2));

        // using Char.CompareTo(Char) Method
        // returns 25 as this instance follows
        // ch3
        Console.WriteLine('Z'.CompareTo(ch3));
    }
}

Output:

0
-13
25

Char.CompareTo(Object) Method

This method is used to compare this instance to a specified object and check this instance precedes, follows, or appears in the same position in the sort order as the specified Object. The value of any instance of Char is considered greater than null.

Syntax:

public int CompareTo(object obj);

Parameter:

obj: It is the required object which is to be compared with this instance or null.

Return Type: It returns a signed number that shows the position of the instance in the sort order in relation to the obj parameter. The return type of this method is System.Int32. The different case for the return values are shown in the below table:

Return value	Description
Less than zero	This instance precedes obj.
Zero	This instance has the same position in the sort as in obj.
Greater than zero	This instance follows obj or obj is null.

Exception: If the obj is not Char object then this method will give ArgumentException.

Example:

C#

// C# program to illustrate the
// Char.CompareTo(Object) Method
using System;

class GeeksforGeeks {

    // Main method
    public static void Main()
    {

        // declaration of data type
        char ch1 = 'G';
        char ch2 = 'a';
        char ch3 = 'B';
        int output;

        // compare ch1 with G, as they are
        // equal so output will be zero
        output = ch1.CompareTo('G');
        Console.WriteLine(output);

        // compare ch3 with ch2
        // output is -31 which means
        // ch3 is less than ch2 by -31
        output = ch3.CompareTo(ch2);
        Console.WriteLine(output);

        // compare ch1 with ch3
        // output is 5 which means
        // ch1 is greater than ch3 by 5
        output = ch1.CompareTo(ch3);
        Console.WriteLine(output);
    }
}

Output:

0
-31
5

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