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String.IndexOf Method (Char, Int32)

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

Namespace: System
Assembly: mscorlib (in mscorlib.dll)

public int IndexOf (
	char value,
	int startIndex
)
public int IndexOf (
	char value, 
	int startIndex
)
public function IndexOf (
	value : char, 
	startIndex : int
) : int
Not applicable.

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.

Exception typeCondition

ArgumentOutOfRangeException

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

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 '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 code example demonstrates the IndexOf method.

// 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

*/

// Sample for String.IndexOf(Char, Int32)
import System.*;

class Sample
{
    public static void main(String[] args)
    {
        String br1 = "0----+----1----+----2----+----3----+----4----+----5----"
            + "+----6----+-";
        String br2 = "01234567890123456789012345678901234567890123456789012345"
            + "67890123456";
        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}.", 
            (Int32)(str.get_Length() - 1));
        Console.Write("{1}{0}", Environment.get_NewLine(), br1);
        Console.Write("{1}{0}", Environment.get_NewLine(), br2);
        Console.WriteLine("{1}{0}", Environment.get_NewLine(), str);
        Console.Write("The letter 't' occurs at position(s): ");

        at = 0;
        start = 0;
        while (start < str.get_Length() && at > -1) {
            at = str.IndexOf('t', start);
            if (at == -1) {
                break;
            }
            Console.Write("{0} ", (Int32)at);
            start = at + 1;
        }
        Console.WriteLine();
    } //main
} //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

*/

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0

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