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String.IndexOf Method (Char, Int32)

.NET Framework 1.1

Reports the index of the first occurrence of the specified Unicode character in this instance. The search starts at a specified character position.

[Visual Basic]
Overloads Public Function IndexOf( _
   ByVal value As Char, _
   ByVal startIndex As Integer _
) As Integer
[C#]
public int IndexOf(
 char value,
 int startIndex
);
[C++]
public: int IndexOf(
 __wchar_t value,
 int startIndex
);
[JScript]
public function IndexOf(
   value : Char,
 startIndex : int
) : int;

Parameters

value
A Unicode character to seek.
startIndex
The search starting position.

Return Value

The index position of value if that character is found, or -1 if it is not.

Exceptions

Exception Type Condition
ArgumentOutOfRangeException startIndex is less than zero or specifies a position beyond the end of this instance.

Remarks

Index numbering starts from zero.

The search ranges from startIndex to the end of the string.

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 '' (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.

Example

[Visual Basic, C#, C++] The following example demonstrates the IndexOf method.

[Visual Basic] 
' Sample for String.IndexOf(Char, Int32)
Imports System

Class Sample
   Public Shared 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 'Main
End Class 'Sample
'
'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
'
'

[C#] 
// Sample for String.IndexOf(Char, Int32)
using System;

class Sample {
    public static void Main() {

    string br1 = "0----+----1----+----2----+----3----+----4----+----5----+----6----+-";
    string br2 = "0123456789012345678901234567890123456789012345678901234567890123456";
    string str = "Now is the time for all good men to come to the aid of their party.";
    int start;
    int at;

    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) && (at > -1))
        {
        at = str.IndexOf('t', start);
        if (at == -1) break;
        Console.Write("{0} ", at);
        start = at+1;
        }
    Console.WriteLine();
    }
}
/*
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

*/

[C++] 
// Sample for String::IndexOf(Char, Int32)
#using <mscorlib.dll>

using namespace System;

int main() {

   String* br1 = S"0----+----1----+----2----+----3----+----4----+----5----+----6----+-";
   String* br2 = S"0123456789012345678901234567890123456789012345678901234567890123456";
   String* str = S"Now is the time for all good men to come to the aid of their party.";
   int start;
   int at;

   Console::WriteLine();
   Console::WriteLine(S"All occurrences of 't' from position 0 to {0}.", __box( str->Length-1));
   Console::WriteLine(S"{1}{0}{2}{0}{3}{0}", Environment::NewLine, br1, br2, str);
   Console::Write(S"The letter 't' occurs at position(s): ");

   at = 0;
   start = 0;
   while((start < str->Length) && (at > -1)) {
      at = str->IndexOf('t', start);
      if (at == -1) break;
      Console::Write(S"{0} ", __box( at));
      start = at+1;
   }
   Console::WriteLine();
}
/*
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

*/

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework, Common Language Infrastructure (CLI) Standard

See Also

String Class | String Members | System Namespace | String.IndexOf Overload List | Int32 | Char | IndexOfAny | LastIndexOf | LastIndexOfAny

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