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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
)

Parameters

oldValue
Type: System.String

The string to be replaced.

newValue
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. If oldValue is not found in the current instance, the method returns the current instance unchanged.

ExceptionCondition
ArgumentNullException

oldValue is null.

ArgumentException

oldValue is the empty string ("").

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

NoteNote

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.

Because this method returns the modified string, you can chain together successive calls to the Replace method to perform multiple replacements on the original string. Method calls are executed from left to right. The following example provides an illustration.

using System;

public class Example
{
   public static void Main()
   {
      String s = "aaa";
      Console.WriteLine("The initial string: '{0}'", s);
      s = s.Replace("a", "b").Replace("b", "c").Replace("c", "d");
      Console.WriteLine("The final string: '{0}'", s);
   }
}
// The example displays the following output: 
//       The initial string: 'aaa' 
//       The final string: 'ddd'
using System;

public class Example
{
   public static void Main()
   {
      String s = new String('a', 3);
      Console.WriteLine("The initial string: '{0}'", s);
      s = s.Replace('a', 'b').Replace('b', 'c').Replace('c', 'd');
      Console.WriteLine("The final string: '{0}'", s);
   }
}
// The example displays the following output: 
//       The initial string: 'aaa' 
//       The final string: 'ddd'

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: 4.6, 4.5, 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

.NET for Windows Store apps

Supported in: Windows 8

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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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