SO WIRD'S GEMACHT: Mithilfe von Visual C++ .NET allgemeine Datei-I/O-Vorgänge durchführen

Eine Textdatei lesen

  listbox1->Items->Clear();
   	try   
	{    
		String* textFile = String::Concat(windir,                                    (S"\\mytest.txt")); 
	        StreamReader *reader=new  StreamReader(textFile);
		do
		{
		    listbox1->Items->Add(reader->ReadLine());
		}   
		while(reader->Peek() != -1);
	}      
         
	catch (System::Exception *e)
	{ 
		listbox1->Items->Add(e);
	}

}

Eine Textdatei schreiben

StreamWriter* pwriter = new StreamWriter(S"c:\\KBTest.txt");
pwriter->WriteLine(S"File created using StreamWriter class.");
pwriter->Close();
listbox1->Items->Clear();
String *filew = new String(S"File Written to C:\\KBTest.txt");
listbox1->Items->Add(filew);

Dateiinformationen anzeigen

 listbox1->Items->Clear();
 String* testfile = String::Concat(windir, (S"\\notepad.exe")); 
 FileInfo *pFileProps  =new FileInfo(testfile);

 listbox1->Items->Add(String::Concat(S"File Name = ", (pFileProps->get_FullName() )) );
 listbox1->Items->Add(String::Concat(S"Creation Time = ", (pFileProps->get_CreationTime() ).ToString()) );
 listbox1->Items->Add(String::Concat(S"Last Access Time = "  ,(pFileProps->get_LastAccessTime() ).ToString()) );
 listbox1->Items->Add(String::Concat(S"Last Write Time = ", (pFileProps->get_LastWriteTime() ).ToString()) );
 listbox1->Items->Add(String::Concat(S"Size = ", (pFileProps->get_Length() ).ToString()) );

Laufwerke auflisten

  listbox1->Items->Clear();
  String* drives[] = Directory::GetLogicalDrives();
  int numDrives = drives->get_Length();
  for (int i=0; i<numDrives; i++)
  {
	listbox1->Items->Add(drives[i]);
  } 

Unterordner auflisten

listbox1->Items->Clear();
String* dirs[] = Directory::GetDirectories(windir);
int numDirs = dirs->get_Length();
for (int i=0; i<numDirs; i++)
{
listbox1->Items->Add(dirs[i]);
}

Dateien auflisten

 listbox1->Items->Clear(); String* files[]= Directory::GetFiles(this->windir); int numFiles = files->get_Length(); for (int i=0; i<numFiles; i++) {   listbox1->Items->Add(files[i]); }

Beispiel mit schrittweiser Anleitung

1. Erstellen Sie in Visual C++ .NET eine neue verwaltete C++-Anwendung.
2. Öffnen Sie das Codefenster für <project name> .cpp.
3. Löschen Sie den gesamten Code.
4. Fügen Sie folgenden Code in <project name>.cpp ein:
   

   #using <mscorlib.dll>
   using namespace System;
   using namespace System::IO;
   
   // required dlls for WinForms
   #using "System.dll"
   #using "System.Windows.Forms.dll"
   #using "System.Drawing.dll"
   
   // required namespaces for WinForms
   using namespace System::ComponentModel;
   using namespace System::Windows::Forms;
   using namespace System::Drawing;
   
   __gc class WinForm: public Form 
   {
   private:
   		
   	Button	    *button1;
   	Button	    *button2;
   	Button	    *button3;
   	Button	    *button4;
   	Button	    *button5;
   	Button	    *button6;
   	String*     windir;
   	ListBox     *listbox1;
   	String	    *caption;	// Caption of the WinForm
   	int	    width;		// width of the WinForm
   	int	    height;		// height of the WinForm
   
   public:
   	WinForm() 
   	{
   		// Set caption and size of the WinForm
   		caption = "Form1";
   		width = 360;
   		height = 273;
   		windir=System::Environment::GetEnvironmentVariable("windir");
   		InitForm();
   	}
   
   	void Dispose()
   	{
   	// Form is being destroyed.  Do any necessary clean-up here.
   
   		Form::Dispose();
   	}
   
   void InitForm()
   {
   		// Setup controls here
   		// Basic WinForm Settings
   	
   		SuspendLayout();
   
   		// button1
   		// 
                   button1 = new Button();
   		button1->Text = "button1";
   		button1->Name = "button1";
   		button1->Size = Drawing::Size(112, 23);
   		button1->TabIndex = 1;
   		button1->Location = Drawing::Point(216,32);
   		button1->Click += (new EventHandler(this,                                       &WinForm::button1_Click));
   		Controls->Add(button1);
   
   		// button2
   		// 
   		button2 = new Button();
   		button2->Text = "button2";
   		button2->Name = "button2";
   		button2->Size = Drawing::Size(112, 23);
   		button2->TabIndex = 2;
   		button2->Location = Drawing::Point(216,64);
   		button2->Click += (new EventHandler(this,                                   &WinForm::button2_Click));
   		Controls->Add(button2);
   		
   		// button3
   		// 
   		button3 = new Button();
   		button3->Text = "button3";
   		button3->Name = "button3";
   		button3->Size = Drawing::Size(112, 23);
   		button3->TabIndex = 3;
   		button3->Location = Drawing::Point(216,96);
   		button3->Click += (new EventHandler(this,                                   &WinForm::button3_Click));
   		Controls->Add(button3);
   
   		// listbox1
   		// 
   		listbox1 = new ListBox();
   		listbox1->Text = "Listbox1";
   		listbox1->Name = "Listbox1";
   		listbox1->Size = Drawing::Size(176, 199);
   		listbox1->TabIndex = 0;
   		listbox1->Location = Drawing::Point(24,24);
   		Controls->Add(listbox1);
   			
   		// 
   		// button4
   		// 
   		button4 = new Button();
   		button4->Text = "button4";
   		button4->Name = "button4";
   		button4->Size = Drawing::Size(112, 23);
   		button4->TabIndex = 4;
   		button4->Location = Drawing::Point(216,128);
   		button4->Click += (new EventHandler(this,                                    &WinForm::button4_Click));
   		Controls->Add(button4);
   
   		// button5
   		// 
   		button5 = new Button();
   		button5->Text = "button5";
   		button5->Name = "button5";
   		button5->Size = Drawing::Size(112, 23);
   		button5->TabIndex = 5;
   		button5->Location = Drawing::Point(216,160);
   		button5->Click += (new EventHandler(this,                                   &WinForm::button5_Click));
   		Controls->Add(button5);
   
   		// button6
   		// 
   		button6 = new Button();
   		button6->Text = "button6";
   		button6->Name = "button6";
   		button6->Size = Drawing::Size(112, 23);
   		button6->TabIndex = 6;
   		button6->Location = Drawing::Point(216,192);
   		button6->Click += (new EventHandler(this,                                   &WinForm::button6_Click));
   		Controls->Add(button6);
   
   		Text = caption;
   		Size = System::Drawing::Size(width, height);
   	
   		Name = "Form1";
   		Text = "Form1";
   		Load += new System::EventHandler(this, Form1_Load);
   		ResumeLayout(false);
   
   }
   
   void button6_Click(Object *sender, EventArgs *e)
   {
   //how to obtain list of files (example uses Windows folder)
   	listbox1->Items->Clear();
   	String* files[]= Directory::GetFiles(this->windir);
   	int numFiles = files->get_Length();
   	for (int i=0; i<numFiles; i++)
   	{
   	 listbox1->Items->Add(files[i]);
   	}
   }
   
   void button1_Click(Object *sender, EventArgs *e)
   {
   //how to read a text file
   //try...catch is to deal with a 0 byte file or non-existant file
   	listbox1->Items->Clear();
      
   	try   
   	{    
   	    String* textFile = String::Concat(windir,                                             ("\\mytest.txt")); 
   	    StreamReader *reader=new  StreamReader(textFile);
   	    do
   	    {
   		listbox1->Items->Add(reader->ReadLine());
   	    }   
   	    while(reader->Peek() != -1);
   	}      
            
   	catch (System::Exception *e)
   	{ 
   	    listbox1->Items->Add(e);
   	}
   
   }
   
    void Form1_Load(Object *sender, EventArgs *e)
   {
   	button1->Text = "Read Text File";
   	button2->Text = "Write Text File";
   	button3->Text = "View File Information";
   	button4->Text = "List Drives";
   	button5->Text = "List Subfolders";
   	button6->Text = "List Files";
   }
   
   void button5_Click(Object *sender, EventArgs *e)
   {         
   //how to get a list of folders (example uses Windows folder) 
   	listbox1->Items->Clear();
   	String* dirs[] = Directory::GetDirectories(windir);
   	int numDirs = dirs->get_Length();
   	for (int i=0; i<numDirs; i++)
   	{
   		listbox1->Items->Add(dirs[i]);
                                                         
   	}
   }
   
   void button4_Click(Object *sender, EventArgs *e)
   {
   //demonstrates  how to obtain a list of disk drives
   	listbox1->Items->Clear();
   	String* drives[] = Directory::GetLogicalDrives();
   	int numDrives = drives->get_Length();
   	for (int i=0; i<numDrives; i++)
   	{
   		listbox1->Items->Add(drives[i]);
   	}
   }
   
   void button3_Click(Object *sender, EventArgs *e)
   {   
   //how to retrieve file properties (example uses notepad.exe)
    listbox1->Items->Clear();
    String* testfile = String::Concat(windir, (S"\\notepad.exe")); 
    FileInfo *pFileProps  =new FileInfo(testfile);
   
    listbox1->Items->Add(String::Concat(S"File Name = ", (pFileProps->get_FullName() )) );
    listbox1->Items->Add(String::Concat(S"Creation Time = ", (pFileProps->get_CreationTime() ).ToString()) );
    listbox1->Items->Add(String::Concat(S"Last Access Time = "  ,(pFileProps->get_LastAccessTime() ).ToString()) );
    listbox1->Items->Add(String::Concat(S"Last Write Time = ", (pFileProps->get_LastWriteTime() ).ToString()) );
    listbox1->Items->Add(String::Concat(S"Size = ", (pFileProps->get_Length() ).ToString()) );
   }
         
   
   void button2_Click(Object *sender, EventArgs *e)
   {
   //demonstrates how to create and write to a text file
     StreamWriter* pwriter = new StreamWriter("c:\\KBTest.txt");
     pwriter->WriteLine("File created using StreamWriter class.");
     pwriter->Close();
     listbox1->Items->Clear();
     String *filew = new String(S"File Written to C:\\KBTest.txt");
     listbox1->Items->Add(filew);
   }
   };
   
   
   void main()
   {
   	// This line creates an instance of WinForm, and 
   	// uses it as the Main Window of the application. 
   	Application::Run(new WinForm());
   }

5. Klicken Sie im Projektmappen-Explorer mit der rechten Maustaste auf den Projektnamen. Klicken Sie danach auf Eigenschaften. Wählen Sie C/C++, und klicken Sie danach auf Vorkompilierte Header. Ändern Sie die Einstellung von Erstellen/Verwenden eines vorkompilierten Headers in Vorkompilierte Header nicht verwenden um, und speichern Sie anschließend das Projekt.
6. Drücken Sie die Taste [F5], um die Anwendung zu erstellen und auszuführen. Klicken Sie auf die Schaltflächen, um die verschiedenen Aktionen anzuzeigen.

Zum Anfang | Ihr Feedback an uns