WebHeaderCollection.Set Method

Reference

Definition

Namespace:: System.Net

Assemblies:: netstandard.dll, System.Net.WebHeaderCollection.dll

Assembly:: System.Net.WebHeaderCollection.dll

Assembly:: System.dll

Assembly:: netstandard.dll

Important

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Sets the specified header to the specified value.

Overloads

Set(HttpRequestHeader, String)	Sets the specified header to the specified value.
Set(HttpResponseHeader, String)	Sets the specified header to the specified value.
Set(String, String)	Sets the specified header to the specified value.

Set(HttpRequestHeader, String)

Source:: WebHeaderCollection.cs

Source:: WebHeaderCollection.cs

Source:: WebHeaderCollection.cs

Sets the specified header to the specified value.

public:
 void Set(System::Net::HttpRequestHeader header, System::String ^ value);

public void Set(System.Net.HttpRequestHeader header, string? value);

public void Set(System.Net.HttpRequestHeader header, string value);

override this.Set : System.Net.HttpRequestHeader * string -> unit

Public Sub Set (header As HttpRequestHeader, value As String)

Parameters

header: HttpRequestHeader

The HttpRequestHeader value to set.

value: String

The content of the header to set.

Exceptions

ArgumentOutOfRangeException

.NET Framework and .NET Core versions 2.0 - 3.1 only: The length of value is greater than 65535.

InvalidOperationException

This WebHeaderCollection instance does not allow instances of HttpRequestHeader.

Remarks

If the header specified in the header does not exist, the Set method inserts a new header into the list of header name/value pairs.

If the header specified in header is already present, value replaces the existing value.

Note

The length of value is validated only in .NET Framework and .NET Core versions 2.0 - 3.1.

On all applicable .NET Framework versions: A WebHeaderCollection instance that's returned by the Headers property will throw an ArgumentOutOfRangeException if the length of value is greater than 65535. All other WebHeaderCollection instances accept a value of any length.
On .NET Core versions through version 3.1: A WebHeaderCollection instance used with any header of type HttpResponseHeader will throw an ArgumentOutOfRangeException if the length of value is greater than 65535. All other WebHeaderCollection instances accept a value of any length.
On .NET 5 and later versions: WebHeaderCollection accepts a value of any length.

Applies to

.NET 9 and other versions

Product	Versions
.NET	Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework	2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard	2.0, 2.1

Set(HttpResponseHeader, String)

Source:: WebHeaderCollection.cs

Source:: WebHeaderCollection.cs

Source:: WebHeaderCollection.cs

Sets the specified header to the specified value.

public:
 void Set(System::Net::HttpResponseHeader header, System::String ^ value);

public void Set(System.Net.HttpResponseHeader header, string? value);

public void Set(System.Net.HttpResponseHeader header, string value);

override this.Set : System.Net.HttpResponseHeader * string -> unit

Public Sub Set (header As HttpResponseHeader, value As String)

Parameters

header: HttpResponseHeader

The HttpResponseHeader value to set.

value: String

The content of the header to set.

Exceptions

ArgumentOutOfRangeException

.NET Framework and .NET Core versions 2.0 - 3.1 only: The length of value is greater than 65535.

InvalidOperationException

This WebHeaderCollection instance does not allow instances of HttpResponseHeader.

Remarks

If the header specified in the header does not exist, the Set method inserts a new header into the list of header name/value pairs.

If the header specified in header is already present, value replaces the existing value.

Note

The length of value is validated only in .NET Framework and .NET Core versions 2.0 - 3.1.

On all applicable .NET Framework versions: A WebHeaderCollection instance that's returned by the Headers property will throw an ArgumentOutOfRangeException if the length of value is greater than 65535. All other WebHeaderCollection instances accept a value of any length.
On .NET Core versions through version 3.1: A WebHeaderCollection instance used with any header of type HttpResponseHeader will throw an ArgumentOutOfRangeException if the length of value is greater than 65535. All other WebHeaderCollection instances accept a value of any length.
On .NET 5 and later versions: WebHeaderCollection accepts a value of any length.

Applies to

.NET 9 and other versions

Product	Versions
.NET	Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework	2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard	2.0, 2.1

Set(String, String)

Source:: WebHeaderCollection.cs

Source:: WebHeaderCollection.cs

Source:: WebHeaderCollection.cs

Sets the specified header to the specified value.

public:
 override void Set(System::String ^ name, System::String ^ value);

public override void Set(string name, string? value);

public override void Set(string name, string value);

override this.Set : string * string -> unit

Public Overrides Sub Set (name As String, value As String)

Parameters

name: String

The header to set.

value: String

The content of the header to set.

Exceptions

ArgumentNullException

name is null or Empty.

ArgumentOutOfRangeException

.NET Framework and .NET Core versions 2.0 - 3.1 only: The length of value is greater than 65535.

ArgumentException

name is a restricted header.

-or-

name or value contain invalid characters.

Examples

The following example uses the Set method to set the value of an existing header.

try
{
   // Create a web request for S"www.msn.com".
   HttpWebRequest^ myHttpWebRequest = dynamic_cast<HttpWebRequest^>(WebRequest::Create( "http://www.msn.com" ));

   // Get the headers associated with the request.
   WebHeaderCollection^ myWebHeaderCollection = myHttpWebRequest->Headers;

   // Set the Cache-Control header in the request.
   myWebHeaderCollection->Set( "Cache-Control", "no-cache" );

   // Get the associated response for the above request.
   HttpWebResponse^ myHttpWebResponse = dynamic_cast<HttpWebResponse^>(myHttpWebRequest->GetResponse());
   Console::WriteLine( "Headers after 'Set' method is used on Cache-Control :" );

   // Print the headers for the request.
   PrintHeaders( myWebHeaderCollection );
   myHttpWebResponse->Close();
}
// Catch exception if trying to set a restricted header.
catch ( ArgumentException^ e ) 
{
   Console::WriteLine( "ArgumentException is thrown. Message is : {0}", e->Message );
}
catch ( WebException^ e ) 
{
   Console::WriteLine( "WebException is thrown. Message is : {0}", e->Message );
   if ( e->Status == WebExceptionStatus::ProtocolError )
   {
      Console::WriteLine( "Status Code : {0}", (dynamic_cast<HttpWebResponse^>(e->Response))->StatusCode );
      Console::WriteLine( "Status Description : {0}", (dynamic_cast<HttpWebResponse^>(e->Response))->StatusDescription );
      Console::WriteLine( "Server : {0}", (dynamic_cast<HttpWebResponse^>(e->Response))->Server );
   }
}
catch ( Exception^ e ) 
{
   Console::WriteLine( "Exception is thrown. Message is : {0}", e->Message );
}

try {
    // Create a web request for "www.msn.com".
    HttpWebRequest myHttpWebRequest = (HttpWebRequest) WebRequest.Create("http://www.msn.com");

    // Get the headers associated with the request.
    WebHeaderCollection myWebHeaderCollection = myHttpWebRequest.Headers;

    // Set the Cache-Control header in the request.
    myWebHeaderCollection.Set("Cache-Control", "no-cache");

    // Get the associated response for the above request.
    HttpWebResponse myHttpWebResponse = (HttpWebResponse) myHttpWebRequest.GetResponse();

    Console.WriteLine ("Headers after 'Set' method is used on Cache-Control :");
    // Print the headers for the request.
    PrintHeaders(myWebHeaderCollection);
    myHttpWebResponse.Close();
}
// Catch exception if trying to set a restricted header.
catch(ArgumentException e) {
    Console.WriteLine("ArgumentException is thrown. Message is :" + e.Message);
}
catch(WebException e) {
    Console.WriteLine("WebException is thrown. Message is :" + e.Message);
    if(e.Status == WebExceptionStatus.ProtocolError) {
        Console.WriteLine("Status Code : {0}", ((HttpWebResponse)e.Response).StatusCode);
        Console.WriteLine("Status Description : {0}", ((HttpWebResponse)e.Response).StatusDescription);
        Console.WriteLine("Server : {0}", ((HttpWebResponse)e.Response).Server);
    }
}
catch(Exception e) {
    Console.WriteLine("Exception is thrown. Message is :" + e.Message);
}

Public Shared Sub Main()

Try
        'Create a web request for "www.msn.com".
        Dim myHttpWebRequest As HttpWebRequest = CType(WebRequest.Create("http://www.msn.com"), HttpWebRequest)
        
        'Get the headers associated with the request.
        Dim myWebHeaderCollection As WebHeaderCollection = myHttpWebRequest.Headers
        
        'Set the Cache-Control header in the request.
        myWebHeaderCollection.Set("Cache-Control", "no-cache")

        'Get the associated response for the above request.
        Dim myHttpWebResponse As HttpWebResponse = CType(myHttpWebRequest.GetResponse(), HttpWebResponse)
        
    Console.WriteLine ("Headers after 'Set' method is used on Cache-Control :")
        'Print the headers for the request.
        PrintHeaders(myWebHeaderCollection)
        myHttpWebResponse.Close()
   'Catch exception if trying to set a restricted header.
    Catch e As ArgumentException
        Console.WriteLine(e.Message)
    Catch e As WebException
        Console.WriteLine(e.Message)
        If e.Status = WebExceptionStatus.ProtocolError Then
            Console.WriteLine("Status Code : {0}", CType(e.Response, HttpWebResponse).StatusCode)
            Console.WriteLine("Status Description : {0}", CType(e.Response, HttpWebResponse).StatusDescription)
            Console.WriteLine("Server : {0}", CType(e.Response, HttpWebResponse).Server)
        End If
    Catch e As Exception
        Console.WriteLine(e.Message)
    End Try
End Sub

Note

The length of value is validated only in .NET Framework and .NET Core versions 2.0 - 3.1.

On all applicable .NET Framework versions: A WebHeaderCollection instance that's returned by the Headers property will throw an ArgumentOutOfRangeException if the length of value is greater than 65535. All other WebHeaderCollection instances accept a value of any length.
On .NET Core versions through version 3.1: A WebHeaderCollection instance used with any header of type HttpResponseHeader will throw an ArgumentOutOfRangeException if the length of value is greater than 65535. All other WebHeaderCollection instances accept a value of any length.
On .NET 5 and later versions: WebHeaderCollection accepts a value of any length.

Remarks

If the header specified in the header does not exist, the Set method inserts a new header into the list of header name/value pairs.

If the header specified in header is already present, value replaces the existing value.

Applies to

.NET 9 and other versions

Product	Versions
.NET	Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework	1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard	2.0, 2.1

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WebHeaderCollection.Set Method

Definition

Overloads

Set(HttpRequestHeader, String)

Parameters

Exceptions

Remarks

Applies to

Set(HttpResponseHeader, String)

Parameters

Exceptions

Remarks

Applies to

Set(String, String)

Parameters

Exceptions

Examples

Remarks

Applies to

Additional resources