String.IndexOf Method (Char, Int32)
Reports the zero-based index of the first occurrence of the specified Unicode character in this string. The search starts at a specified character position.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- value
-
Type:
System.Char
A Unicode character to seek.
- startIndex
-
Type:
System.Int32
The search starting position.
Return Value
Type: System.Int32The zero-based index position of value from the start of the string if that character is found, or -1 if it is not.
| Exception | Condition |
|---|---|
| ArgumentOutOfRangeException | startIndex is less than 0 (zero) or greater than the length of the string. |
Index numbering starts from 0. The startIndex parameter can range from 0 to the length of the string instance. If startIndex equals the length of the string instance, the method returns -1.
The search ranges from startIndex to the end of the string.
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.
The following example demonstrates the IndexOf method.
' Sample for String.IndexOf(Char, Int32) Module Sample Sub Main() Dim br1 As String = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-" Dim br2 As String = "0123456789012345678901234567890123456789012345678901234567890123456" Dim str As String = "Now is the time for all good men to come to the aid of their party." Dim start As Integer Dim at As Integer Console.WriteLine() Console.WriteLine("All occurrences of 't' from position 0 to {0}.", str.Length - 1) Console.WriteLine("{1}{0}{2}{0}{3}{0}", Environment.NewLine, br1, br2, str) Console.Write("The letter 't' occurs at position(s): ") at = 0 start = 0 While start < str.Length AndAlso at > -1 at = str.IndexOf("t"c, start) If at = -1 Then Exit While End If Console.Write("{0} ", at) start = at + 1 End While Console.WriteLine() End Sub End Module ' 'This example produces the following results: ' 'All occurrences of 't' from position 0 to 66. '0----+----1----+----2----+----3----+----4----+----5----+----6----+- '0123456789012345678901234567890123456789012345678901234567890123456 'Now is the time for all good men to come to the aid of their party. ' 'The letter 't' occurs at position(s): 7 11 33 41 44 55 64 ' '
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1