C# | StringComparer.Compare Method

Last Updated : 30 Jun, 2019

StringComparer.Compare Method is used to compare two objects or strings and returns an indication of their relative sort order. There are 2 methods in the overload list of this method:

Compare(Object, Object)

Compare(String, String)

Compare(Object, Object)

This method compares two objects and returns an indication of their relative sort order when overridden in a derived class.

Syntax:

public int Compare (object a, object b);

Here, a is the 1st object and b is the 2nd object to be compared with each other.

Returns: This method returns a signed integer that indicates the relative values of the object a and b. The values are returned according to the following table:

Value	Meaning
Less than zero	a precedes b in the sort order or a is null and b is not null.
Zero	a is equal to b or a and b are both null.
Greater than zero	a follows b in the sort order or b is null and a is not null.

Exception: This method will give ArgumentException if neither a nor b is a String object, and neither a nor b implements the IComparable interface.

Example:

// C# program to demonstrate the use of 
// StringComparer.Compare(Object, Object) 
// Method 
using System; 
using System.Collections; 
  
class gfg { 
  
    public class cmp : IComparer { 
  
        // CaseInsensitiveComparer 
        int IComparer.Compare(Object x, Object y) 
        { 
            return ((new CaseInsensitiveComparer()).Compare(x, y)); 
        } 
    } 
  
    // Main Method 
    public static void Main() 
    { 
        // Initialize a string array. 
        string[] arr = {"A", "E", "D", "C", "B"}; 
  
        // Display original array 
        Console.WriteLine("Original array:"); 
        print(arr); 
  
        // Sort the array using the default comparer. 
        Array.Sort(arr); 
        Console.WriteLine("Sort using sort function:"); 
        print(arr); 
  
        // Sort the array using the comparer. 
        Array.Sort(arr, new cmp()); 
        Console.WriteLine("Sorting using compare method :"); 
        print(arr); 
    } 
  
    // print function 
    public static void print(IEnumerable list) 
    { 
        foreach(var v in list) 
            Console.WriteLine(v); 
  
        Console.WriteLine(); 
    } 
} 

Output:

Original array:
A
E
D
C
B

Sort using sort function:
A
B
C
D
E

Sorting using compare method :
A
B
C
D
E

Compare(String, String)

This method compares two strings and returns an indication of their relative sort order when overridden in a derived class.

Syntax:

public abstract int Compare (string a, string b);

Here, a is the 1st string and b is the 2nd string to be compared with each other.

Returns: This method returns a signed integer that indicates the relative values of the object a and b. The values are returned according to the following table:

Value	Meaning
Less than zero	a precedes b in the sort order or a is null and b is not null.
Zero	a is equal to b or a and b are both null.
Greater than zero	a follows b in the sort order or b is null and a is not null.

Exception: This method will give ArgumentException if neither a nor b is a String object, and neither a nor b implements the IComparable interface.

Example:

// C# program to demonstrate the use of  
// StringComparer.Compare(String, String) 
// Method 
using System; 
using System.Collections.Generic; 
  
class GFG { 
  
    // Main Method 
    static void Main(string[] args) 
    { 
        string s1 = "geek"; 
        string s2 = "Geek"; 
  
        int st = 0; 
  
        // Compare(string, string) method 
        st = string.Compare(s1, s2); 
  
        Console.WriteLine(st.ToString()); 
    } 
} 