String.ToLowerInvariant Method ()


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Returns a copy of this String object converted to lowercase using the casing rules of the invariant culture.

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

member ToLowerInvariant : unit -> string

Return Value

Type: System.String

The lowercase equivalent of the current string.

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. For more information, see the CultureInfo.InvariantCulture property.

If your application depends on the case of a string changing in a predictable way that is unaffected by the current culture, use the ToLowerInvariant method. The ToLowerInvariant method is equivalent to ToLower(CultureInfo.InvariantCulture). The method is recommended when a collection of strings must appear in a predictable order in a user interface control.


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 converted to lowercase.

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 defines a string array that contains a single word in a number of languages. The ToLowerInvariant method is used to populate the elements of a parallel array with the case-insensitive version of each word. The Array.Sort<'TKey, 'TValue>('TKey[], 'TValue[], IComparer<'TKey>) method is used to sort the case-sensitive array based on the order of elements in the lowercase array to ensure that elements appear in the same order regardless of language.

No code example is currently available or this language may not be supported.

Universal Windows Platform
Available since 8
.NET Framework
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Available since 4.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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