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The General Winforms Interview Questions consists the most frequently
asked questions in Winforms. This list of 100+ questions guage your familiarity
with the Winforms platform. The q&a have been collected over a period
of time from various blogs, forums and other similar Winforms sites
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1. Windows Forms Deployment
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| 1.1 How can I run an
EXE from within my application?
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| 1.2 What are the
common issues in redirecting assemblies using the publisher policy files?
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| 1.3 How can I find
all programs with a GUI (not just arbitrary windows) that are running on my
local machine?
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| 1.4 How can I get a
list of all processes running on my system?
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| 1.5 How can I make
sure there is only one instance of my application running?
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| 1.6 How do I
determine which operating system is running?
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| 1.7 How can I get
all IP addresses for my local machine?
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| 1.8 My user does not
have .NET installed. Will he be able to run my Windows Forms application?
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| 1.9 How do I get the
path to my running EXE?
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| 1.10 How can I
programmatically obtain the name of the assembly that the code is executing in
?
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| 1.11 How can I see
what is installed in the Global Assembly on a machine?
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| 1.12 How do I set
the company name that is returned by
System.Windows.Forms.Application.CompanyName?
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1.1 How can I run an EXE from within my application?
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Use the Process class found in the System.Diagnostics namespace.
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[C#]
Process proc = new Process();
proc.StartInfo.FileName = @"Notepad.exe";
proc.StartInfo.Arguments = ""; proc.Start();
[VB.NET]
Dim proc As New Process()
proc.StartInfo.FileName = "Notepad.exe"
proc.StartInfo.Arguments = ""
proc.Start()
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1.2 What are the common issues in redirecting assemblies using the publisher
policy files?
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1) Make sure to follow proper naming conventions for the policy
dll. For example, if the original assembly name is TestAssembly.dll then the
corresponding policy assembly should be called "policy.1.0.TestAssembly.dll" to
make this redirection work for all "1.0.*" version bindings of the original
assembly.
2) While specifying the name for the assembly in the policy
file, do not include the ".dll" extension. This is wrong:
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>assemblyIdentity name="TestAssembly.dll"
publicKeyToken="f638d0a8d5996dd4" culture="neutral" /<
Instead use:
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>assemblyIdentity name="TestAssembly" publicKeyToken="f638d0a8d5996dd4"
culture="neutral" /<
3) Make sure to sign the policy assembly with the same strong
name as the original.
4) Make sure to distribute the policy file along with the
policy assembly. Installing the policy assembly in the GAC alone will not
suffice. Note that any change made to the policy file after creating the policy
assembly will not take effect.
5) Always use /link (to the policy file) in the "al" command
while creating the policy assembly. Do not use /embed. It doesn't seem to be
supported.
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1.3 How can I find all programs with a GUI (not just arbitrary windows) that
are running on my local machine?
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You could use EnumWindows with p/Invoke, but using the static
Process.GetProcesses() found in the System.Diagnostics namespace will avoid the
interop overhead.
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[C#]
Using System.Diagnostics;
...
foreach ( Process p in Process.GetProcesses(System.Environment.MachineName) )
{
if( p.MainWindowHandle != IntPtr.Zero)
{
//this is a GUI app
Console.WriteLine( p ); // string s = p.ToString();
}
}
[VB.NET]
Imports System.Diagnostics
...
Dim p As Process
For Each p In Process.GetProcesses(System.Environment.MachineName)
If p.MainWindowHandle <> IntPtr.Zero Then
'this is a GUI app
Console.WriteLine(p) ' string s = p.ToString();
End If
Next p
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There is one potential problem on Windows 98. If a process was started with
ProcessStartInfo.UseShellExecute set to true, this MainWindowHandle is not
available.
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1.4 How can I get a list of all processes running on my system?
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Use the static Process.GetProcesses() found in the System.Diagnostics
namespace.
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[C#]
Using System.Diagnostics;
...
foreach ( Process p in Process.GetProcesses() )
Console.WriteLine( p ); // string s = p.ToString();
[VB.NET]
Imports System.Diagnostics
...
Dim p As Process
For Each p In Process.GetProcesses()
Console.WriteLine(p) ' string s = p.ToString()
Next p
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1.5 How can I make sure there is only one instance of my application running?
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In it, we uses the Process class in System.Diagnostics to implement this
functionality using code such as
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[C#]
public static Process RunningInstance()
{
Process current = Process.GetCurrentProcess();
Process[] processes = Process.GetProcessesByName (current.ProcessName);
//Loop through the running processes in with the same name
foreach (Process process in processes)
{
//Ignore the current process
if (process.Id != current.Id)
{
//Make sure that the process is running from the exe file.
if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") ==
current.MainModule.FileName)
{
//Return the other process instance.
return process;
}
}
}
//No other instance was found, return null.
return null;
}
[VB.NET]
Public Shared Function RunningInstance() As Process
Dim current As Process = Process.GetCurrentProcess()
Dim processes As Process() = Process.GetProcessesByName(current.ProcessName)
'Loop through the running processes in with the same name
Dim process As Process
For Each process In processes
'Ignore the current process
If process.Id <> current.Id Then
'Make sure that the process is running from the exe file.
If [Assembly].GetExecutingAssembly().Location.Replace("/", "\") =
current.MainModule.FileName Then
'Return the other process instance.
Return process
End If
End If
Next process
'No other instance was found, return null.
Return Nothing
End Function 'RunningInstance
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1.6 How do I determine which operating system is running?
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The Environment class in the System namespace has this information.
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[C#]
string versionText = Environment.OSVersion.Version.ToString();
[VB.NET]
Dim versionText As String = Environment.OSVersion.Version.ToString()
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1.7 How can I get all IP addresses for my local machine?
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[C#]
string s ="";
System.Net.IPAddress[] addressList =
Dns.GetHostByName(Dns.GetHostName()).AddressList;
for (int i = 0; i < addressList.Length; i ++)
{
s += addressList[i].ToString() + "\n";
}
textBox1.Text = s;
[VB.NET]
Dim s As String = ""
Dim addressList As System.Net.IPAddress() =
Dns.GetHostByName(Dns.GetHostName()).AddressList
Dim i As Integer
For i = 0 To addressList.Length - 1
s += addressList(i).ToString() + ControlChars.Lf
Next i
textBox1.Text = s
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1.8 My user does not have .NET installed. Will he be able to run my Windows
Forms application?
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No, the .NET runtime platform has to be on any machine that will run your
Windows Forms application. Microsoft has made the .NET runtime platform
installation (dotnetredist.exe) available as a free download from Microsoft
.NET Framework Redistributable .
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1.9 How do I get the path to my running EXE?
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The Application class has a static member ExecutablePath that has this
information.
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[C#] textBox1.Text = Application.ExecutablePath;
[VB.NET] TextBox1.Text = Application.ExecutablePath
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1.10 How can I programmatically obtain the name of the assembly that the code
is executing in ?
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The following code snippet demonstrates how you can obtain the name of the
assembly that the code is executing in:
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[C#]
MessageBox.Show(System.Reflection.Assembly.GetEntryAssembly().GetName().Name);
[VB.NET]
MessageBox.Show(System.Reflection.Assembly.GetEnTryAssembly().GetName().Name)
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1.11 How can I see what is installed in the Global Assembly on a machine?
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Use Windows Explorer to view the C:\WINNT\assembly folder. If the .NET
Framework is installed, the Windows Explorer will show a custom view of this
folder. Use the detailed view to see the details of each assembly.
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1.12 How do I set the company name that is returned by
System.Windows.Forms.Application.CompanyName?
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This is an assembly attribute. The VS development environment sets it in the
AssemblyInfo.cs (vb) file. If you open that file, you will see a block of
assembly attributes that you can set, including company and version numbers.
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