Returns a copy of this String object converted to uppercase using the casing rules of the invariant culture.
Assembly: mscorlib (in mscorlib.dll)
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 Using the 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 method. The method is equivalent to ToUpper(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 uppercase.
The casing operation that results from calling the ToLower method takes the casing conventions of the current culture into account. 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 method. This produces the same result in every culture (unlike the ToLower method) and performs more efficiently.
The following example defines a string array that contains a single word in a number of languages. The 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 uppercase array to ensure that elements appear in the same order regardless of language.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.