Article
11/17/2011

Regex.Replace Method (String, String, String, RegexOptions)

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Within a specified input string, replaces all strings that match a specified regular expression with a specified replacement string. Specified options modify the matching operation.

Namespace: System.Text.RegularExpressions
Assembly: System (in System.dll)

Syntax

'Declaration
Public Shared Function Replace ( _
    input As String, _
    pattern As String, _
    replacement As String, _
    options As RegexOptions _
) As String

public static string Replace(
    string input,
    string pattern,
    string replacement,
    RegexOptions options
)

Parameters

input
Type: System.String
The string to search for a match.

pattern
Type: System.String
The regular expression pattern to match.

replacement
Type: System.String
The replacement string.

options
Type: System.Text.RegularExpressions.RegexOptions
A bitwise combination of the enumeration values.

Return Value

Type: System.String
A new string that is identical to the input string, except that a replacement string takes the place of each matched string.

Exceptions

Exception	Condition
ArgumentException	A regular expression parsing error occurred.
ArgumentNullException	input is nulla null reference (Nothing in Visual Basic). -or- pattern is nulla null reference (Nothing in Visual Basic). -or- replacement is nulla null reference (Nothing in Visual Basic).
ArgumentOutOfRangeException	options is not a valid bitwise combination of RegexOptions values.

ArgumentException

A regular expression parsing error occurred.

ArgumentNullException

input is nulla null reference (Nothing in Visual Basic).

-or-

pattern is nulla null reference (Nothing in Visual Basic).

-or-

replacement is nulla null reference (Nothing in Visual Basic).

ArgumentOutOfRangeException

options is not a valid bitwise combination of RegexOptions values.

Remarks

The static Replace methods are equivalent to constructing a Regex object with the specified regular expression pattern and calling the instance method Replace.

The pattern parameter consists of various regular expression language elements that symbolically describe the string to match. For more information about regular expressions, see Regular Expression Language Elements in the .NET Framework documentation. If the options parameter specifies the RightToLeft enumeration value, the search for matches begins from the end of the input string and proceeds from right to left; otherwise, the search begins from the start of the input string and proceeds from left to right.

The replacement parameter specifies the string that is to replace each match in input. replacement can consist of any combination of literal text and substitutions. For example, the replacement pattern a*${test}b inserts the string "a*" followed by the substring that is matched by the test capturing group, if any, followed by the string "b". The * character is not recognized as a metacharacter within a replacement pattern.

Note:
Substitutions are the only regular expression language elements that are recognized in a replacement pattern. All other regular expression language elements, including character escapes, are allowed in regular expression patterns only and are not recognized in replacement patterns.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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