SystemInformation.Network Property
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Gets a value indicating whether a network connection is present.
public:
static property bool Network { bool get(); };public static bool Network { get; }static member Network : boolPublic Shared ReadOnly Property Network As BooleanProperty Value
true if a network connection is present; otherwise, false.
Examples
The following code example lists all properties of the SystemInformation class in a ListBox and displays the current value of the property in a TextBox when a list item selected.
#using <System.Windows.Forms.dll>
#using <System.Drawing.dll>
#using <System.dll>
using namespace System;
using namespace System::Collections;
using namespace System::ComponentModel;
using namespace System::Drawing;
using namespace System::Reflection;
using namespace System::Windows::Forms;
public ref class SystemInfoBrowserForm: public System::Windows::Forms::Form
{
private:
System::Windows::Forms::ListBox^ listBox1;
System::Windows::Forms::TextBox^ textBox1;
public:
SystemInfoBrowserForm()
{
this->SuspendLayout();
InitForm();
// Add each property of the SystemInformation class to the list box.
Type^ t = System::Windows::Forms::SystemInformation::typeid;
array<PropertyInfo^>^pi = t->GetProperties();
for ( int i = 0; i < pi->Length; i++ )
listBox1->Items->Add( pi[ i ]->Name );
textBox1->Text = String::Format( "The SystemInformation class has {0} properties.\r\n", pi->Length );
// Configure the list item selected handler for the list box to invoke a
// method that displays the value of each property.
listBox1->SelectedIndexChanged += gcnew EventHandler( this, &SystemInfoBrowserForm::listBox1_SelectedIndexChanged );
this->ResumeLayout( false );
}
private:
void listBox1_SelectedIndexChanged( Object^ /*sender*/, EventArgs^ /*e*/ )
{
// Return if no list item is selected.
if ( listBox1->SelectedIndex == -1 )
return;
// Get the property name from the list item.
String^ propname = listBox1->Text;
if ( propname->Equals( "PowerStatus" ) )
{
// Cycle and display the values of each property of the PowerStatus property.
textBox1->Text = String::Concat( textBox1->Text, "\r\nThe value of the PowerStatus property is:" );
Type^ t = System::Windows::Forms::PowerStatus::typeid;
array<PropertyInfo^>^pi = t->GetProperties();
for ( int i = 0; i < pi->Length; i++ )
{
Object^ propval = pi[ i ]->GetValue( SystemInformation::PowerStatus, nullptr );
textBox1->Text = String::Format( "{0}\r\n PowerStatus.{1} is: {2}", textBox1->Text, pi[ i ]->Name, propval );
}
}
else
{
// Display the value of the selected property of the SystemInformation type.
Type^ t = System::Windows::Forms::SystemInformation::typeid;
array<PropertyInfo^>^pi = t->GetProperties();
PropertyInfo^ prop = nullptr;
for ( int i = 0; i < pi->Length; i++ )
if ( pi[ i ]->Name == propname )
{
prop = pi[ i ];
break;
}
Object^ propval = prop->GetValue( nullptr, nullptr );
textBox1->Text = String::Format( "{0}\r\nThe value of the {1} property is: {2}", textBox1->Text, propname, propval );
}
}
void InitForm()
{
// Initialize the form settings
this->listBox1 = gcnew System::Windows::Forms::ListBox;
this->textBox1 = gcnew System::Windows::Forms::TextBox;
this->listBox1->Anchor = (System::Windows::Forms::AnchorStyles)(System::Windows::Forms::AnchorStyles::Top | System::Windows::Forms::AnchorStyles::Bottom | System::Windows::Forms::AnchorStyles::Left | System::Windows::Forms::AnchorStyles::Right);
this->listBox1->Location = System::Drawing::Point( 8, 16 );
this->listBox1->Size = System::Drawing::Size( 172, 496 );
this->listBox1->TabIndex = 0;
this->textBox1->Anchor = (System::Windows::Forms::AnchorStyles)(System::Windows::Forms::AnchorStyles::Top | System::Windows::Forms::AnchorStyles::Bottom | System::Windows::Forms::AnchorStyles::Right);
this->textBox1->Location = System::Drawing::Point( 188, 16 );
this->textBox1->Multiline = true;
this->textBox1->ScrollBars = System::Windows::Forms::ScrollBars::Vertical;
this->textBox1->Size = System::Drawing::Size( 420, 496 );
this->textBox1->TabIndex = 1;
this->ClientSize = System::Drawing::Size( 616, 525 );
this->Controls->Add( this->textBox1 );
this->Controls->Add( this->listBox1 );
this->Text = "Select a SystemInformation property to get the value of";
}
};
[STAThread]
int main()
{
Application::Run( gcnew SystemInfoBrowserForm );
}
using System;
using System.Collections;
using System.ComponentModel;
using System.Drawing;
using System.Reflection;
using System.Windows.Forms;
namespace SystemInfoBrowser
{
public class SystemInfoBrowserForm : System.Windows.Forms.Form
{
private System.Windows.Forms.ListBox listBox1;
private System.Windows.Forms.TextBox textBox1;
public SystemInfoBrowserForm()
{
this.SuspendLayout();
InitForm();
// Add each property of the SystemInformation class to the list box.
Type t = typeof(System.Windows.Forms.SystemInformation);
PropertyInfo[] pi = t.GetProperties();
for( int i=0; i<pi.Length; i++ )
listBox1.Items.Add( pi[i].Name );
textBox1.Text = "The SystemInformation class has "+pi.Length.ToString()+" properties.\r\n";
// Configure the list item selected handler for the list box to invoke a
// method that displays the value of each property.
listBox1.SelectedIndexChanged += new EventHandler(listBox1_SelectedIndexChanged);
this.ResumeLayout(false);
}
private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
{
// Return if no list item is selected.
if( listBox1.SelectedIndex == -1 ) return;
// Get the property name from the list item.
string propname = listBox1.Text;
if( propname == "PowerStatus" )
{
// Cycle and display the values of each property of the PowerStatus property.
textBox1.Text += "\r\nThe value of the PowerStatus property is:";
Type t = typeof(System.Windows.Forms.PowerStatus);
PropertyInfo[] pi = t.GetProperties();
for( int i=0; i<pi.Length; i++ )
{
object propval = pi[i].GetValue(SystemInformation.PowerStatus, null);
textBox1.Text += "\r\n PowerStatus."+pi[i].Name+" is: "+propval.ToString();
}
}
else
{
// Display the value of the selected property of the SystemInformation type.
Type t = typeof(System.Windows.Forms.SystemInformation);
PropertyInfo[] pi = t.GetProperties();
PropertyInfo prop = null;
for( int i=0; i<pi.Length; i++ )
if( pi[i].Name == propname )
{
prop = pi[i];
break;
}
object propval = prop.GetValue(null, null);
textBox1.Text += "\r\nThe value of the "+propname+" property is: "+propval.ToString();
}
}
private void InitForm()
{
// Initialize the form settings
this.listBox1 = new System.Windows.Forms.ListBox();
this.textBox1 = new System.Windows.Forms.TextBox();
this.listBox1.Anchor = ((System.Windows.Forms.AnchorStyles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom)
| System.Windows.Forms.AnchorStyles.Left) | System.Windows.Forms.AnchorStyles.Right)));
this.listBox1.Location = new System.Drawing.Point(8, 16);
this.listBox1.Size = new System.Drawing.Size(172, 496);
this.listBox1.TabIndex = 0;
this.textBox1.Anchor = ((System.Windows.Forms.AnchorStyles)(((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom)
| System.Windows.Forms.AnchorStyles.Right)));
this.textBox1.Location = new System.Drawing.Point(188, 16);
this.textBox1.Multiline = true;
this.textBox1.ScrollBars = System.Windows.Forms.ScrollBars.Vertical;
this.textBox1.Size = new System.Drawing.Size(420, 496);
this.textBox1.TabIndex = 1;
this.ClientSize = new System.Drawing.Size(616, 525);
this.Controls.Add(this.textBox1);
this.Controls.Add(this.listBox1);
this.Text = "Select a SystemInformation property to get the value of";
}
[STAThread]
static void Main()
{
Application.Run(new SystemInfoBrowserForm());
}
}
}
Imports System.Collections
Imports System.ComponentModel
Imports System.Drawing
Imports System.Reflection
Imports System.Windows.Forms
Public Class SystemInfoBrowserForm
Inherits System.Windows.Forms.Form
Private listBox1 As System.Windows.Forms.ListBox
Private textBox1 As System.Windows.Forms.TextBox
Public Sub New()
Me.SuspendLayout()
InitForm()
' Add each property of the SystemInformation class to the list box.
Dim t As Type = GetType(System.Windows.Forms.SystemInformation)
Dim pi As PropertyInfo() = t.GetProperties()
Dim i As Integer
For i = 0 To pi.Length - 1
listBox1.Items.Add(pi(i).Name)
Next i
textBox1.Text = "The SystemInformation class has " + pi.Length.ToString() + " properties." + ControlChars.CrLf
' Configure the list item selected handler for the list box to invoke a
' method that displays the value of each property.
AddHandler listBox1.SelectedIndexChanged, AddressOf listBox1_SelectedIndexChanged
Me.ResumeLayout(False)
End Sub
Private Sub listBox1_SelectedIndexChanged(sender As Object, e As EventArgs)
' Return if no list item is selected.
If listBox1.SelectedIndex = - 1 Then
Return
End If
' Get the property name from the list item.
Dim propname As String = listBox1.Text
If propname = "PowerStatus" Then
' Cycle and display the values of each property of the PowerStatus property.
textBox1.Text += ControlChars.CrLf + "The value of the PowerStatus property is:"
Dim t As Type = GetType(System.Windows.Forms.PowerStatus)
Dim pi As PropertyInfo() = t.GetProperties()
Dim i As Integer
For i = 0 To pi.Length - 1
Dim propval As Object = pi(i).GetValue(SystemInformation.PowerStatus, Nothing)
textBox1.Text += ControlChars.CrLf + " PowerStatus." + pi(i).Name + " is: " + propval.ToString()
Next i
Else
' Display the value of the selected property of the SystemInformation type.
Dim t As Type = GetType(System.Windows.Forms.SystemInformation)
Dim pi As PropertyInfo() = t.GetProperties()
Dim prop As PropertyInfo = Nothing
Dim i As Integer
For i = 0 To pi.Length - 1
If pi(i).Name = propname Then
prop = pi(i)
Exit For
End If
Next i
Dim propval As Object = prop.GetValue(Nothing, Nothing)
textBox1.Text += ControlChars.CrLf + "The value of the " + propname + " property is: " + propval.ToString()
End If
End Sub
Private Sub InitForm()
' Initialize the form settings
Me.listBox1 = New System.Windows.Forms.ListBox()
Me.textBox1 = New System.Windows.Forms.TextBox()
Me.listBox1.Anchor = CType(System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Bottom Or System.Windows.Forms.AnchorStyles.Left Or System.Windows.Forms.AnchorStyles.Right, System.Windows.Forms.AnchorStyles)
Me.listBox1.Location = New System.Drawing.Point(8, 16)
Me.listBox1.Size = New System.Drawing.Size(172, 496)
Me.listBox1.TabIndex = 0
Me.textBox1.Anchor = CType(System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Bottom Or System.Windows.Forms.AnchorStyles.Right, System.Windows.Forms.AnchorStyles)
Me.textBox1.Location = New System.Drawing.Point(188, 16)
Me.textBox1.Multiline = True
Me.textBox1.ScrollBars = System.Windows.Forms.ScrollBars.Vertical
Me.textBox1.Size = New System.Drawing.Size(420, 496)
Me.textBox1.TabIndex = 1
Me.ClientSize = New System.Drawing.Size(616, 525)
Me.Controls.Add(Me.textBox1)
Me.Controls.Add(Me.listBox1)
Me.Text = "Select a SystemInformation property to get the value of"
End Sub
<STAThread()> _
Shared Sub Main()
Application.Run(New SystemInfoBrowserForm())
End Sub
End Class
Remarks
The Network property indicates whether the system has a currently established network connection.
Note
This property always returns true on all Windows platforms supported by .NET Framework. Use the System.Net.NetworkInformation namespace to retrieve more accurate network status.
Applies to
See also
Dolgozzon együtt velünk a GitHubon
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