String::IndexOf Method (String, Int32, StringComparison)

Reports the zero-based index of the first occurrence of the specified string in the current String object. Parameters specify the starting search position in the current string and the type of search to use for the specified string.

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

int IndexOf(
	String^ value, 
	int startIndex, 
	StringComparison comparisonType


Type: System::String

The String object to seek.

Type: System::Int32

The search starting position.

Type: System::StringComparison

One of the System::StringComparison values.

Return Value

Type: System::Int32
The zero-based index position of the value parameter if that string is found, or -1 if it is not. If value is String::Empty, the return value is startIndex.


value is nullptr.


startIndex is less than zero or greater than the length of this string.


comparisonType is not a valid System::StringComparison value.

Index numbering starts from 0 (zero). 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 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 IndexOf method that find the first 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.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0

.NET Compact Framework

Supported in: 3.5, 2.0

XNA Framework

Supported in: 3.0, 2.0, 1.0




Clarified the relationship between string length and the startIndex parameter.

Content bug fix.

Noted that an exception is not thrown for an empty string if the index parameter is invalid.

Content bug fix.

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