{"id":2572,"date":"2023-07-03T13:49:52","date_gmt":"2023-07-03T06:49:52","guid":{"rendered":"https:\/\/csharptutorial.net\/?page_id=2572"},"modified":"2023-07-03T14:36:53","modified_gmt":"2023-07-03T07:36:53","slug":"csharp-string-tolower","status":"publish","type":"page","link":"https:\/\/www.csharptutorial.net\/csharp-string-methods\/csharp-string-tolower\/","title":{"rendered":"C# String ToLower"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you will learn how to use the C# String ToLower()<\/code> method to convert a string to lowercase.<\/p>\n\n\n\n

Introduction to the C# ToLower() method<\/h2>\n\n\n\n

The String<\/a> ToLower()<\/code> method returns a copy of the current string converted to lowercase. Here’s the syntax of the ToLower()<\/code> method:<\/p>\n\n\n

public<\/span> string ToLower();<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
For example, the following program uses the ToLower()<\/code> method to convert the message \"Hello, World!\"<\/code> to lowercase:<\/p>\n\n\n
using<\/span> static<\/span> System.Console;\n\nvar<\/span> message = \"Hello, World!\"<\/span>;\nvar<\/span> lower = message.ToLower();\n\nWriteLine(lower);<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
hello, world!<\/code><\/span><\/pre>\n\n\n
By default, the ToLower()<\/code> method considers the case rule of the current culture. If you want to convert a string to lowercase using a specific culture, you can use the following overload of the ToLower()<\/code> method:<\/p>\n\n\n
public<\/span> string<\/span> ToLower<\/span> (\n   System<\/span>.Globalization<\/span>.CultureInfo<\/span>? culture<\/span>\n);<\/code><\/span>Code language:<\/span> CSS<\/span> (<\/span>css<\/span>)<\/span><\/small><\/pre>\n\n\n
In this syntax, the culture<\/code> is an instance of CultureInfo<\/code> that specifies a culture-specific casing rule.<\/p>\n\n\n\n
The following example demonstrates how using different CultureInfo<\/code> objects can lead to different lowercase conversions based on specific language rules:<\/p>\n\n\n
using System.Globalization;\nusing static<\/span> System.Console;\n\nvar<\/span> s = \"Istanbul \u0130ZM\u0130R Ankara\"<\/span>;\n\n\/\/ Using the default (English) culture<\/span>\nvar<\/span> englishLowercase = s.ToLower(CultureInfo.InvariantCulture);\nWriteLine(\"Default (English) lowercase: \"<\/span> + englishLowercase);\n\n\/\/ Using the Turkish culture<\/span>\nvar<\/span> turkishCulture = new<\/span> CultureInfo(\"tr-TR\"<\/span>);\nvar<\/span> turkishLowercase = s.ToLower(turkishCulture);\nConsole.WriteLine(\"Turkish lowercase: \"<\/span> + turkishLowercase);<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, we have a string that contains Turkish characters, such as \"\u0130\"<\/code> (capital i<\/code> with a dot) and \"\u0130\"<\/code> (small i<\/code> with a dot) which are specific to the Turkish alphabet.<\/p>\n\n\n\n
When we  use the ToLower()<\/code> to convert a string to lowercase using the default culture (English), the method uses the English rules for lowercase conversion, and we get \"istanbul \u0130ZM\u0130R ankara\"<\/code>.<\/p>\n\n\n\n
However, when we use the ToLower()<\/code> method with the Turkish culture (\"tr-TR\"<\/code>), the method uses Turkish-specific lowercase rules for conversion. <\/p>\n\n\n\n
In Turkish, the lowercase equivalent of \"\u0130\"<\/code> is \"i\"<\/code> without a dot, and the lowercase equivalent of \"I\"<\/code> is \"\u0131\"<\/code> (a dotless i). As a result, the Turkish lowercase string becomes \"i\u0307stanbul i\u0307zmir ankara\"<\/code>.<\/p>\n\n\n\n
C# String ToLowerInvariant()<\/h2>\n\n\n\n
The String ToLowerInvariant()<\/code> returns a lowercase version of a string using the casing rules of the invariant culture.<\/p>\n\n\n\n
Here’s the syntax of the ToLowerInvariant()<\/code> method:<\/p>\n\n\n
public<\/span> string ToLowerInvariant();<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The ToLowerInvariant()<\/code> method is equivalent to the ToLower()<\/code> method with the CultureInfo.InvariantCulture<\/code> argument:<\/p>\n\n\n
ToLower<\/span>(CultureInfo<\/span>.InvariantCulture<\/span>)<\/code><\/span>Code language:<\/span> CSS<\/span> (<\/span>css<\/span>)<\/span><\/small><\/pre>\n\n\n
One practical example of using the ToLowerInvariant()<\/code> method is when you need to perform a case-sensitive string comparison.<\/p>\n\n\n\n
Using ToLowerInvariant()<\/code> ensures consistent behavior and avoids potential issues with culture-specific rules.<\/p>\n\n\n\n
The following example demonstrates how to use the ToLowerInvariant()<\/code> method to check if the input username is in a list:<\/p>\n\n\n
using static<\/span> System.Console;\r\n\r\n\r\/\/ Get the username from input<\/span>\r\nWrite(\"Enter you username:\"<\/span>);\r\nvar<\/span> searchUsername = ReadLine();\r\n\r\n\/\/ Username list<\/span>\r\nvar<\/span> usernames = new<\/span> List<string>{ \"JohnDoe\"<\/span>, \"JaneSmith\"<\/span>, \"MikeJohnson\"<\/span>, \"SarahBrown\"<\/span> };\r\n\r\n\/\/ Check if the username exists<\/span>\r\nvar<\/span> userExists = usernames.Exists(\r\n    username<\/span> =><\/span> username.ToLowerInvariant() == searchUsername?.ToLowerInvariant()\r\n);\r\n\r\n\/\/ Set the message<\/span>\r\nvar<\/span> message = userExists \r\n    ? $\"The user {searchUsername} exists in the list.\"<\/span> \r\n    : $\"The user {searchUsername} does not exist in the list.\"<\/span>;\r\n\r\nWriteLine(message);\r\n<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
Enter<\/span> you<\/span> username<\/span>:johndoe<\/span>\r\nThe<\/span> user<\/span> johndoe<\/span> exists<\/span> in<\/span> the<\/span> list<\/span>.<\/code><\/span>Code language:<\/span> CSS<\/span> (<\/span>css<\/span>)<\/span><\/small><\/pre>\n\n\n
Summary<\/h2>\n\n\n\n
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  • Use the C# String ToLower()<\/code> method to convert a string to lowercase.<\/li>\n<\/ul>\n
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