String.Equality(String, String) Operator

Definition

Namespace:

System

Assembly:

System.Runtime.dll

Source:

String.Comparison.cs

Determines whether two specified strings have the same value.

public:
 static bool operator ==(System::String ^ a, System::String ^ b);

public static bool operator == (string? a, string? b);

static member ( = ) : string * string -> bool

Public Shared Operator == (a As String, b As String) As Boolean

Parameters

a

String

The first string to compare, or null.

b

String

The second string to compare, or null.

Returns

Boolean

true if the value of a is the same as the value of b; otherwise, false.

Examples

The following example demonstrates the equality operator.

// Example for the String Equality operator.
using namespace System;
void CompareAndDisplay( String^ Comparand )
{
   String^ Lower = "abcd";
   Console::WriteLine( "\"{0}\" == \"{1}\" ?  {2}", Lower, Comparand, Lower == Comparand );
}

int main()
{
   Console::WriteLine( "This example of the String Equality operator\n"
   "generates the following output.\n" );
   CompareAndDisplay( "ijkl" );
   CompareAndDisplay( "ABCD" );
   CompareAndDisplay( "abcd" );
}

/*
This example of the String Equality operator 
generates the following output.

"abcd" == "ijkl" ?  False
"abcd" == "ABCD" ?  False
"abcd" == "abcd" ?  True
*/

// Example for the String Equality operator.
using System;

class EqualityOp 
{
    public static void Main() 
    {
        Console.WriteLine( 
            "This example of the String Equality operator\n" +
            "generates the following output.\n" );

        CompareAndDisplay( "ijkl" );
        CompareAndDisplay( "ABCD" );
        CompareAndDisplay( "abcd" );
    }

    static void CompareAndDisplay( string Comparand )
    {
        String  Lower = "abcd";

        Console.WriteLine( 
            "\"{0}\" == \"{1}\" ?  {2}",
            Lower, Comparand, Lower == Comparand );
    }
}

/*
This example of the String Equality operator 
generates the following output.

"abcd" == "ijkl" ?  False
"abcd" == "ABCD" ?  False
"abcd" == "abcd" ?  True
*/

// Example for the String Equality operator.
printfn "This example of the String Equality operator\ngenerates the following output.\n"

let compareAndDisplay comparand =
    let lower = "abcd"
    printfn $"\"%s{lower}\" == \"%s{comparand}\" ?  {lower = comparand}"

compareAndDisplay "ijkl"
compareAndDisplay "ABCD"
compareAndDisplay "abcd"

(*
This example of the String Equality operator 
generates the following output.

"abcd" == "ijkl" ?  False
"abcd" == "ABCD" ?  False
"abcd" == "abcd" ?  True
*)

Remarks

The Equality method defines the operation of the equality operator for the String class. It enables code such as that shown in the Example section. The operator, in turn, calls the static Equals(String, String) method, which performs an ordinal (case-sensitive and culture-insensitive) comparison.

Note

The Visual Basic compiler does not resolve the equality operator as a call to the Equality method. Instead, the equality operator wraps a call to the Operators.CompareString method.