C# | String.ToLowerInvariant Method

Last Updated : 01 Feb, 2019

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# program to illustrate  
// ToLowerInvariant() method 
using System; 
  
class GFG { 
  
    // Main method 
    static public void Main() 
    { 
  
        // varibles 
        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# 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 sting 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 gives you compile time error.

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

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