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String.Replace Method (String, String)

Returns a new string in which all occurrences of a specified string in the current instance are replaced with another specified string.

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

public string Replace(
	string oldValue,
	string newValue


Type: System.String
The string to be replaced.
Type: System.String
The string to replace all occurrences of oldValue.

Return Value

Type: System.String
A string that is equivalent to the current string except that all instances of oldValue are replaced with newValue.


oldValue is null.


oldValue is the empty string ("").

If newValue is null, all occurrences of oldValue are removed.


This method does not modify the value of the current instance. Instead, it returns a new string in which all occurrences of oldValue are replaced by newValue.

This method performs an ordinal (case-sensitive and culture-insensitive) search to find oldValue.

The following example demonstrates how you can use the Replace method to correct a spelling error.

using System;

public class ReplaceTest {
    public static void Main() {

        string errString = "This docment uses 3 other docments to docment the docmentation";

        Console.WriteLine("The original string is:{0}'{1}'{0}", Environment.NewLine, errString);

        // Correct the spelling of "document".

        string correctString = errString.Replace("docment", "document");

        Console.WriteLine("After correcting the string, the result is:{0}'{1}'",
                Environment.NewLine, correctString);
// This code example produces the following output:
// The original string is:
// 'This docment uses 3 other docments to docment the docmentation'
// After correcting the string, the result is:
// 'This document uses 3 other documents to document the documentation'

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.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.
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