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String.LastIndexOf Method (String, Int32, Int32, StringComparison)

Reports the zero-based index position of the last occurrence of a specified string within this instance. Parameters specify the starting search position in the current string, the number of characters in the current string to search, and the type of search to use for the specified string.

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

member LastIndexOf : 
        value:string * 
        startIndex:int * 
        count:int * 
        comparisonType:StringComparison -> int 


Type: System.String
The string to seek.
Type: System.Int32
The search starting position. The search proceeds from startIndex toward the beginning of this instance.
Type: System.Int32
The number of character positions to examine.
Type: System.StringComparison
One of the enumeration values that specifies the rules for the search.

Return Value

Type: System.Int32
The index position of the value parameter if that string is found, or -1 if it is not found or if the current instance equals String.Empty. If value is String.Empty, the return value is the smaller of startIndex and the last index position in this instance.


value is a null reference (Nothing in Visual Basic).


count is negative.


The current instance does not equal String.Empty, and startIndex is negative.


The current instance does not equal String.Empty, and startIndex is greater than the length of this instance.


The current instance does not equal String.Empty, and startIndex - count + 1 specifies a position that is not within this instance.


comparisonType is not a valid System.StringComparison value.

Index numbering starts from zero. That is, the first character in the string is at index zero and the last is at Length - 1.

The search begins at the startIndex character position and proceeds backward 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 comparisonType parameter specifies to search for the value parameter using the current or invariant culture, using a case-sensitive or case-insensitive search, and using word or ordinal comparison rules.

The following example demonstrates three overloads of the LastIndexOf method that find the last occurrence of a string within another string using different values of the StringComparison enumeration.

No code example is currently available or this language may not be supported.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

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.