C# | String.ToLowerInvariant Method

String.ToLowerInvariant Method is used to get a copy of this String object converted to lowercase using the casing rules of the invariant culture. Here, “invariant culture” represents a culture that is culture-insensitive.

Syntax:

public string ToLowerInvariant ();

Return value: The return type of this method is System.String. This method returns a string which is a lowercase equivalent of the current string.

Below given are some examples to understand the implementation in a better way: 

Example 1:

C#

// C# program to illustrate
// ToLowerInvariant() method
using System;

class GFG {

    // Main method
    static public void Main()
    {

        // variables
        string strA = "WelCome tO GeeKSfOrGeeKs";
        string strB;

        // Convert strA into lowercase
        // using ToLowerInvariant() method
        strB = strA.ToLowerInvariant();

        // Display string before ToLowerInvariant() method
        Console.WriteLine("String before ToLowerInvariant:");
        Console.WriteLine(strA);
        Console.WriteLine();

        // Display string after ToLowerInvariant() method
        Console.WriteLine("String after ToLowerInvariant:");
        Console.WriteLine(strB);
    }
}

Output:

String before ToLowerInvariant:
WelCome tO GeeKSfOrGeeKs

String after ToLowerInvariant:
welcome to geeksforgeeks

Example 2:

C#

// C# program to illustrate
// ToLowerInvariant() Method
using System;

public class GFG {

    // Main method
    static public void Main()
    {
        // calling function
        Convert("GEeks");
        Convert("geeks");
        Convert("GEEKS");
    }

    static void Convert(String value)
    {

        // Display  strings
        Console.WriteLine("String 1:  {0}", value);

        // Convert string into Lowercase
        // using ToLowerInvariant() method
        value = value.ToLowerInvariant();

        // Display the Lowercase strings
        Console.WriteLine("String 2:  {0}", value);
    }
}

Output:

String 1:  GEeks
String 2:  geeks
String 1:  geeks
String 2:  geeks
String 1:  GEEKS
String 2:  geeks

Note:

• The invariant culture represents a culture that is culture-insensitive. It is associated with the English language but not with a specific country or region.
• ToLowerInvariant() method does not modify the value of the current instance. Instead, it returns a new string in which all characters in the current instance are converted to lowercase.
• This method can’t be overloaded if you try to overload this method, it will give you compile-time error.

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