C# | String Operators

Last Updated : 22 Feb, 2021

The string is an array of characters. The String class represents the text as a series of Unicode characters and it is defined in the .NET base class library. The main use of the String class is to provide the properties, operators and methods so that it becomes easy to work with strings.
There are two types of operators present in the String class:

Equality(String, String) Operator
Inequality(String, String) Operator

Equality(String, String) Operator

This operator is used to check whether the given string contains the same value or not. It returns true if both the string are equal. Otherwise, return false.
Syntax:

public static bool operator == ( string x, string y );

Parameters:

string x: String x is the first string to compare.
string y: String y is the second string to compare.

Return value: The return type of this operator is System.Boolean. It returns true if string x is equal to string y, otherwise return false.
Example 1:

CSharp

// C# program to illustrate the
// Equality operator
using System;
 
class GFG {
 
    // Main Method
    public static void Main(string[] args)
    {
         
        // variables
        string s1 = "WelcomeToGeeks";
        string s2 = "WelcomeToGeeks";
        string s3 = "Geeksforgeeks";
        bool result1, result2;
 
        // Equality operator return true
        // as both strings are equal
        result1 = s1 == s2;
        Console.WriteLine("s1 is equal to s2: {0} ", result1);
 
        // Equality operator return false
        // as both strings are not equal
        result2 = s1 == s3;
        Console.WriteLine("s1 is equal to s3: {0} ", result2);
    }
}

Output:

s1 is equal to s2: True 
s1 is equal to s3: False

Example 2:

CSharp

// C# program to illustrate 
// the Equality operator
using System;
 
class GFG {
     
    // Main method
    public static void Main()
    {
         
        // function calling
        Check("GEEKS");
        Check("geeks");
        Check("GEEKS");
    }
 
    // Function to check the
    // string for equality
    static void Check(String value)
    {
         
        // string str
        String str = "geeks";
 
        // Display the comparison between strings
        Console.WriteLine("String 1: {0}", str);
        Console.WriteLine("String 2:  {0}", value);
        Console.WriteLine("Comparison of string 1 and string 2: {0}",
                                                      str == value);
    }
}

Output:

String 1: geeks
String 2:  GEEKS
Comparison of string 1 and string 2: False
String 1: geeks
String 2:  geeks
Comparison of string 1 and string 2: True
String 1: geeks
String 2:  GEEKS
Comparison of string 1 and string 2: False

Inequality(string, string) Operator

This operator is used to check whether the given strings contain different values or not. It returns true if both the strings are different from each other. Otherwise, return false.
Syntax:

public static bool operator != ( string x, string y );

Parameters:

string x: String x is the first string to compare.
string y: String y is the second string to compare.

Return Value: The return type of this operator is System.Boolean. It returns true if string x is not equal to string y, otherwise return false.
Below given are some examples to understand the implementation in a better way:
Example 1:

CSharp

// C# program to illustrate the
// Inequality operator
using System;
 
class GFG {
 
    // Main Method
    public static void Main(string[] args)
    {
         
        // variables
        string s1 = "WelcomeToGeeks";
        string s2 = "WelcomeToGeeks";
        string s3 = "Geeksforgeeks";
        bool result1, result2;
 
        // Inequality operator return true
        // as both strings are different from each other
        result1 = s1 != s3;
        Console.WriteLine("s1 is different from s3: {0} ", result1);
 
        // Inequality operator return false
        // as both strings are equal
        result2 = s1 != s2;
        Console.WriteLine("s1 is different from s2: {0} ", result2);
    }
}

Output:

s1 is different from s3: True 
s1 is different from s2: False

Example 2:

CSharp

// C# program to illustrate the concept
// of Inequality operator
using System;
 
class GFG {
     
    // main method
    public static void Main()
    {
         
        // function calling
        Check("GEEKS");
        Check("geeks");
        Check("GEEKS");
    }
 
    // method to check the string value
    static void Check(String value)
    {
         
        // string str
        String str = "geeks";
 
        // Display the comparison between strings
        Console.WriteLine("string 1: {0}", str);
        Console.WriteLine("string 2:  {0}", value);
        Console.WriteLine("Comparison of string 1 and string 2: {0}",
                                                       str != value);
    }
}

Output:

string 1: geeks
string 2:  GEEKS
Comparison of string 1 and string 2: True
string 1: geeks
string 2:  geeks
Comparison of string 1 and string 2: False
string 1: geeks
string 2:  GEEKS
Comparison of string 1 and string 2: True

Reference: https://docs.microsoft.com/en-us/dotnet/api/system.string?view=netframework-4.7.2#operators