Windows form < Use texbox values for system commands

[peewster]

Hi all,

i just started playing with gui apps. My first test is a small ping app.

I've created a new project (windows forms) containing:

1: image
2: textbox
3: 2 x button (1 exit, 1 ping)

Now when i click on exit, the app extits... "really "

When i click on ping, i''m getting a popup with the information from the textfield. This is cool, but i want to run the system command ping with the textbox value.

This is what i have:

#pragma endregion
	private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {
				 Application::Exit();
			 }
	
	private: System::Void button2_Click(System::Object^  sender, System::EventArgs^  e) {
				 
				 String^ result = textBox1->Text;
				 MessageBox::Show( result );
////////////// When i comment the messagebox and try:
                                 system("ping -n 2 " + result + " > C:\\pingtest.txt");
////////////// i get errors (shown below)
			 }
	private: System::Void textBox1_TextChanged(System::Object^  sender, System::EventArgs^  e) {
			 
			 }
};

ERROR:

error C2664: 'system' : cannot convert parameter 1 from 'System::String ^' to 'const char *'

Only with:

 
private: System::Void button2_Click(System::Object^  sender, System::EventArgs^  e) {
	 system("ping -n 2 www.google.nl > C:\\pingtest.txt");
}

it does work, but i can't use the textbox value.

So i need to convert "result" i think, but i don't know how to do this correctly and let ping run with the result as parameter

Any ideas ?

[Paul McKenzie]

Managed C++ and Windows Forms questions are off-topic for this forum.

You want the Managed C++ forum.

Regards,

Paul McKenzie

[peewster]

Managed C++ and Windows Forms questions are off-topic for this forum.

You want the Managed C++ forum.

Regards,

Paul McKenzie

Ow sorry, can somebody move this thread for me ?

[Eri523]

The error message tells it all: You try to pass a managed string to the function, but that expects a native C-string (a native array of char), and there's no implicit conversion available. (There is one in the opposite direction, though, which is why you can assign a plain quoted string literal to a managed string.)

Now you could get the raw characters out of the managed string by means of the Encoding::GetBytes() method, but that would return a managed array that would need further conversion (and probably wouldn't even be null-terminated unless you append "\0" to the managed string prior to conversion). Since I prefer doing things the .NET way in .NET (the "Romans" thing... ) whenever possible, I refrained from further research at this point.

Here's a purely .NET-based function that (for the most part) emulates the behavior of the C library system() function and probably isn't significantly more complicated than all that string conversion mumbo-jumbo either:

// Usual namespace stuff omitted

using namespace Diagnostics;
using namespace IO;

int WinSystem(String ^strCommand)
{
  if (strCommand) {
    ProcessStartInfo ^psi = gcnew ProcessStartInfo(Environment::GetEnvironmentVariable("ComSpec"),
      "/c " + strCommand);
    psi->UseShellExecute = false;
    Process ^proc = Process::Start(psi);
    proc->WaitForExit();
    int nExitCode = proc->ExitCode;
    delete proc;
    return nExitCode;
  } else
    return File::Exists(Environment::GetEnvironmentVariable("ComSpec"));
}

Here's a related thread (in the right forum section ) that, among other things, demonstrates a more elegant way to get hands on the shell command output than redirecting it to a temporary file (which as such wouln't work with the unmodified function above, though): http://forums.codeguru.com/showthrea...Extern-“C”

Well, now that the thread has a real (non-trivial) .NET reply, I admit it really demands being moved...

peewster, after 80 posts I think you really should know by now that that didn't belong here...

[ovidiucucu]

[ Moved thread ]