String::LastIndexOf Method (Char, Int32, Int32)
Reports the zero-based index position of the last occurrence of the specified Unicode character in a substring within this instance. The search starts at a specified character position and examines a specified number of character positions.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- value
- Type: System::Char
The Unicode character to seek.
- startIndex
- Type: System::Int32
The starting position of the search. The search proceeds from startIndex toward the beginning of this instance.
- count
- Type: System::Int32
The number of character positions to examine.
Return Value
Type: System::Int32The zero-based index position of value if that character is found, or -1 if it is not found or if the current instance equals String::Empty.
| Exception | Condition |
|---|---|
| ArgumentOutOfRangeException | The current instance does not equal String::Empty and startIndex is less than zero, or greater than or equal to the length of this instance. -or- The current instance does not equal String::Empty and startIndex - count + 1 is less than zero. |
Index numbering starts from zero. That is, the first character in the string is at index zero and the last is at Length - 1.
This method begins searching at the startIndex character position of this instance and proceeds backward toward the beginning until either value is found or count character positions have been examined. For example, if startIndex is Length - 1, the method searches backward count characters from the last character in the string. The search 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 value are the same. To perform a culture-sensitive search, use the CompareInfo::LastIndexOf 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 finds the index of all occurrences of a character in a substring, working from the end of the substring to the start of the substring.
// Sample for String::LastIndexOf(Char, Int32, Int32) using namespace System; int 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; int count; int end; start = str->Length - 1; end = start / 2 - 1; Console::WriteLine( "All occurrences of 't' from position {0} to {1}.", start, end ); Console::WriteLine( "\n{0}\n{1}\n{2}", br1, br2, str ); Console::Write( "The letter 't' occurs at position(s): " ); count = 0; at = 0; while ( (start > -1) && (at > -1) ) { count = start - end; //Count must be within the substring. at = str->LastIndexOf( 't', start, count ); if ( at > -1 ) { Console::Write( " {0} ", at ); start = at - 1; } } } /* This example produces the following results: All occurrences of 't' from position 66 to 32. 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): 64 55 44 41 33 */
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.