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String.ToLower Method (CultureInfo)

Updated: October 2008

Returns a copy of this String converted to lowercase, using the casing rules of the specified culture.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

public string ToLower(
	CultureInfo culture


Type: System.Globalization.CultureInfo

A CultureInfo object that supplies culture-specific casing rules.

Return Value

Type: System.String
A String in lowercase.


culture is null.

The casing rules of the culture specified by the culture parameter determine the way the case of the string is changed.


   This 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 lowercased.

Security Considerations

If you need the lowercase or uppercase version of an operating system identifier, such as a file name, named pipe, or registry key, use the ToLowerInvariant or ToUpperInvariant methods.

The following example converts two strings of uppercase characters to lowercase characters using the English-United States and Turkish-Turkey cultures, then compares the lowercase strings. The uppercase strings are identical except that for each occurrence of the Unicode LATIN CAPITAL LETTER I in one string, the other string contains LATIN CAPITAL LETTER I WITH DOT ABOVE.

// Sample for String.ToLower(CultureInfo) 

using System;
using System.Globalization;

class Sample 
    public static void Main() 
    String str1 = "INDIGO";
    // str2 = str1, except each 'I' is '\u0130' (Unicode LATIN CAPITAL I WITH DOT ABOVE).
    String str2 = new String(new Char[] {'\u0130', 'N', 'D', '\u0130', 'G', 'O'});
    String str3, str4;

    Console.WriteLine("str1 = '{0}'", str1);

    Console.WriteLine("str1 is {0} to str2.", 
         ((0 == String.CompareOrdinal(str1, str2)) ? "equal" : "not equal"));
    CodePoints("str1", str1);
    CodePoints("str2", str2);

    // str3 is a lower case copy of str2, using English-United States culture.
    Console.WriteLine("str3 = Lower case copy of str2 using English-United States culture.");
    str3 = str2.ToLower(new CultureInfo("en-US", false));

    // str4 is a lower case copy of str2, using Turkish-Turkey culture.
    Console.WriteLine("str4 = Lower case copy of str2 using Turkish-Turkey culture.");
    str4 = str2.ToLower(new CultureInfo("tr-TR", false));

    // Compare the code points in str3 and str4.
    Console.WriteLine("str3 is {0} to str4.", 
         ((0 == String.CompareOrdinal(str3, str4)) ? "equal" : "not equal"));
    CodePoints("str3", str3);
    CodePoints("str4", str4);

    public static void CodePoints(String title, String s)
    Console.Write("{0}The code points in {1} are: {0}", Environment.NewLine, title);
    foreach (ushort u in s)
      Console.Write("{0:x4} ", u);
This example produces the following results:

str1 = 'INDIGO'

str1 is not equal to str2.

The code points in str1 are:
0049 004e 0044 0049 0047 004f

The code points in str2 are:
0130 004e 0044 0130 0047 004f

str3 = Lower case copy of str2 using English-United States culture.
str4 = Lower case copy of str2 using Turkish-Turkey culture.

str3 is equal to str4.

The code points in str3 are:
0069 006e 0064 0069 0067 006f

The code points in str4 are:
0069 006e 0064 0069 0067 006f

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0




October 2008

Added a note that the method returns a new String object.

Customer feedback.

August 2008

Removed remarks that applied only to the parameterless String.ToLower() method.

Information enhancement.