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) 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 */
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