String.IndexOf Method (Char)
Microsoft Silverlight will reach end of support after October 2021. Learn more.
Reports the zero-based index of the first occurrence of the specified Unicode character in this string.
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public Function IndexOf ( _
value As Char _
) As Integer
public int IndexOf(
char value
)
Parameters
- value
Type: System.Char
A Unicode character to seek.
Return Value
Type: System.Int32
The zero-based index position of value if that character is found, or -1 if it is not.
Remarks
Index numbering starts from zero.
The search for value is case-sensitive.
This method performs an ordinal (culture-insensitive) search, where a character is considered equivalent to another character only if their Unicode scalar values are the same. To perform a culture-sensitive search, use the CompareInfo.IndexOf method, where a Unicode scalar value representing a precomposed character, such as the ligature 'Æ' (U+00C6), might be considered equivalent to any occurrence of the character's components in the correct sequence, such as "AE" (U+0041, U+0045), depending on the culture.
Examples
The following code example demonstrates how you can search a String for a character using the IndexOf method.
' Create a Unicode String with 5 Greek Alpha characters
Dim szGreekAlpha As New String(ChrW(&H319), 5)
' Create a Unicode String with a Greek Omega character
Dim szGreekOmega As New String(New Char() {ChrW(&H3A9), ChrW(&H3A9), _
ChrW(&H3A9)}, 2, 1)
Dim szGreekLetters As String = String.Concat(szGreekOmega, szGreekAlpha, _
szGreekOmega)
' Examine the result
outputBlock.Text &= szGreekLetters & vbCrLf
' The first index of Alpha
Dim iAlpha As Integer = szGreekLetters.IndexOf(ChrW(&H319))
' The last index of Omega
Dim iomega As Integer = szGreekLetters.LastIndexOf(ChrW(&H3A9))
outputBlock.Text &= String.Format("The Greek letter Alpha first appears at index {0}.", _
iAlpha) & vbCrLf
outputBlock.Text &= String.Format("The Greek letter Omega last appears at index {0}.", _
iomega) & vbCrLf
// Create a Unicode String with 5 Greek Alpha characters
String szGreekAlpha = new String('\u0319', 5);
// Create a Unicode String with a Greek Omega character
String szGreekOmega = new String(new char[] { '\u03A9', '\u03A9', '\u03A9' }, 2, 1);
String szGreekLetters = String.Concat(szGreekOmega, szGreekAlpha, szGreekOmega);
// Examine the result
outputBlock.Text += szGreekLetters + "\n";
// The first index of Alpha
int ialpha = szGreekLetters.IndexOf('\u0319');
// The last index of Omega
int iomega = szGreekLetters.LastIndexOf('\u03A9');
outputBlock.Text += "The Greek letter Alpha first appears at index " + ialpha +
" and Omega last appears at index " + iomega + " in this String." + "\n";
Version Information
Silverlight
Supported in: 5, 4, 3
Silverlight for Windows Phone
Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0
XNA Framework
Supported in: Xbox 360, Windows Phone OS 7.0
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.
See Also