String.Substring Method (Int32, Int32)

Updated: October 2008

Retrieves a substring from this instance. The substring starts at a specified character position and has a specified length.

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

public string Substring(
	int startIndex,
	int length
)

Parameters

startIndex
Type: System.Int32

The zero-based starting character position of a substring in this instance.

length
Type: System.Int32

The number of characters in the substring.

Return Value

Type: System.String
A String equivalent to the substring of length length that begins at startIndex in this instance, or Empty if startIndex is equal to the length of this instance and length is zero.

ExceptionCondition
ArgumentOutOfRangeException

startIndex plus length indicates a position not within this instance.

-or-

startIndex or length is less than zero.

startIndex is zero-based.

NoteNote:

   This method does not modify the value of the current instance. Instead, it returns a new string with length characters starting from the startIndex character position in the current instance.

The following example uses the Substring method in three cases to isolate substrings within a string. In two cases the substrings are used in comparisons, and in the third case an exception is thrown because invalid parameters are specified.

String myString = "abc";
bool test1 = myString.Substring(2, 1).Equals("c"); // This is true.
Console.WriteLine(test1);
bool test2 = String.IsNullOrEmpty(myString.Substring(3, 0)); // This is true.
Console.WriteLine(test2);
try {
   string str3 = myString.Substring(3, 1); // This throws ArgumentOutOfRangeException.
   Console.WriteLine(str3);
}
catch (ArgumentOutOfRangeException e) {
   Console.WriteLine(e.Message);
}         

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, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Date

History

Reason

October 2008

Added a note that the method returns a new String object.

Customer feedback.

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