Char.IsLetter Method (String, Int32)
Indicates whether the character at the specified position in a specified string is categorized as a Unicode letter.
Assembly: mscorlib (in mscorlib.dll)
Character positions in a string are indexed starting from zero.
This method determines whether the character at a specified index position in a string is a member of any category of Unicode letter. Unicode letters include the following:
Uppercase letters, such as U+0041 (LATIN CAPITAL LETTER A) through U+005A (LATIN CAPITAL LETTER Z), or U+0400 (CYRILLIC CAPITAL LETTER IE WITH GRAVE) through U+042F (CYRILLIC CAPITAL LETTER YA). These characters are members of the UnicodeCategory.UppercaseLetter category.
Lowercase letters, such as U+0061 (LATIN SMALL LETTER A) through U+007A (LATIN SMALL LETTER Z), or U+03AC (GREEK SMALL LETTER ALPHA WITH TONOS) through U+03CE (GREEK SMALL LETTER OMEGA WITH TONOS). These characters are members of the UnicodeCategory.LowercaseLetter category.
Title case letters, such as U+01C5 (LATIN CAPITAL LETTER D WITH SMALL LETTER Z WITH CARON) or U+1FFC (GREEK CAPITAL LETTER OMEGA WITH PROSGEGRAMMENI). These characters are members of the UnicodeCategory.TitlecaseLetter category.
Modifiers, such as U+02B0 (MODIFIER LETTER SMALL H) through U+02C1 (MODIFIER LETTER REVERSED GLOTTAL STOP), or U+1D2C (MODIFIER LETTER CAPITAL A) through U+1D61 (MODIFIER LETTER SMALL CHI). These characters are members of the UnicodeCategory.ModifierLetter category.
Other letters, such as U+05D0 (HEBREW LETTER ALEF) through U+05EA (HEBREW LETTER TAV), U+0621 (ARABIC LETTER HAMZA) through U+063A (ARABIC LETTER GHAIN), or U+4E00 (<CJK Ideograph, First>) through U+9FC3 (<CJK Ideograph, Last>). These characters are members of the UnicodeCategory.OtherLetter category.
.NET FrameworkSupported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0
.NET Framework Client ProfileSupported in: 4, 3.5 SP1
Portable Class LibrarySupported in: Portable Class Library
.NET for Windows Store appsSupported in: Windows 8
.NET for Windows Phone appsSupported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1
Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.