Open Software Solutions

You can still use the FSO in the .NET Framework. Because the FSO is a COM component, the .NET Framework requires that access to the object be through the Interop layer. The .NET Framework generates a wrapper for the component for you if you want to use the component. However, the File class, the FileInfo class, the Directory class, the DirectoryInfo class, and other related classes in the .NET Framework offer functionality that is not available through the FSO without the overhead of the Interop layer.

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Requirements

The following list outlines the hardware, the software, the network infrastructure, and the service packs that are required:

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Demonstrated file I/O operations

The examples in this article describe basic file I/O operations. The Step-by-step example section describes how to create a sample program that demonstrates the following six file I/O operations:

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Read a text file

The following sample code uses a StreamReader class to read a text file. The contents of the file are added to a ListBox control. The try…catch block is used to warn the program if the file is empty. There are many ways to determine when the end of the file is reached. This sample uses the Peek method to examine the next line before it reads the next line.

listBox1->Items->Clear();try {    String^ textFile = String::Concat(windir,  mytest.txt);    StreamReader^ reader = gcnew StreamReader(textFile);    do    {        listBox1->Items->Add(reader->ReadLine());    }    while(reader->Peek() != -1);}catch(FileNotFoundException^ ex){    listBox1->Items->Add(ex);}catch(System::Exception^ e){    listBox1->Items->Add(e);}

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Write a text file

This sample code uses a StreamWriter class to create and to write to a file. If you have an existing file, you can open it in the same manner.

StreamWriter^ pwriter = gcnew StreamWriter(C:  KBTest.txt);pwriter->WriteLine(File created using StreamWriter class.);pwriter->Close();listBox1->Items->Clear();String ^filew = gcnew String(File Written to C:  KBTest.txt);listBox1->Items->Add(filew);

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View file information

This sample code uses a FileInfo class to access a file’s properties. This sample uses Notepad. The properties appear in a ListBox control.

listBox1->Items->Clear();String^ testfile = String::Concat(windir,  notepad.exe);FileInfo^ pFileProps = gcnew FileInfo(testfile);listBox1->Items->Add(String::Concat(File Name = , pFileProps->FullName));listBox1->Items->Add(String::Concat(Creation Time = , pFileProps->CreationTime.ToString()));listBox1->Items->Add(String::Concat(Last Access Time = , pFileProps->LastAccessTime.ToString()));listBox1->Items->Add(String::Concat(Last Write Time = , pFileProps->LastWriteTime.ToString()));listBox1->Items->Add(String::Concat(Size = , pFileProps->Length.ToString()));

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List disk drives

This sample code uses the Directory class and the Drive class to list the logical drives on a system. For this sample, the results appear in a ListBox control.

listBox1->Items->Clear();cli::array<String^>^ drives = Directory::GetLogicalDrives();int numDrives = drives->Length;for(int i=0; i<numDrives; i++){    listBox1->Items->Add(drives[i]);}

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List subfolders

This sample code uses the GetDirectories method of the Directory class to obtain a list of folders.

listBox1->Items->Clear();cli::array<String^>^ dirs = Directory::GetDirectories(windir);int numDirs = dirs->Length;for(int i=0; i<numDirs; i++){    listBox1->Items->Add(dirs[i]);}

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List files

This sample code uses the GetFiles method of the Directory class to obtain a list of files.

listBox1->Items->Clear();cli::array<String^>^ files = Directory::GetFiles(windir);int numFiles = files->Length;for(int i=0; i<numFiles; i++){    listBox1->Items->Add(files[i]);}

Many things can go wrong when a user gains access to files. The files may not exist, the files may be in use, or users may not have rights on the files in the folders that they are trying to access. Consider these possibilities when you write code to handle the exceptions that may be generated.

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Step-by-step example

private: String^ windir; 

windir = System::Environment::GetEnvironmentVariable(windir);

					// How to read a text file:					// Use try...catch to deal with a 0-byte file or a nonexistent file.					listBox1->Items->Clear();					try {						StreamReader^ reader = gcnew StreamReader(c:  mytest.txt);						do						{							listBox1->Items->Add(reader->ReadLine());						}						while(reader->Peek() != -1);					}					catch(FileNotFoundException^ ex)					{						listBox1->Items->Add(ex);					}					catch(System::Exception^ e)					{						listBox1->Items->Add(e);					}

// This shows you how to create and to write to a text file.StreamWriter^ pwriter = gcnew StreamWriter(c:  KBTest.txt);pwriter->WriteLine(The file was created by using the StreamWriter class.);pwriter->Close();listBox1->Items->Clear();String^ filew = gcnew String(File written to c:  KBTest.txt);listBox1->Items->Add(filew);

// This code retrieves file properties. The example uses Notepad.exe.listBox1->Items->Clear();String^ testfile = String::Concat(windir,  notepad.exe);FileInfo^ pFileProps = gcnew FileInfo(testfile);listBox1->Items->Add(String::Concat(File Name = , pFileProps->FullName));listBox1->Items->Add(String::Concat(Creation Time = , pFileProps->CreationTime.ToString()));listBox1->Items->Add(String::Concat(Last Access Time = , pFileProps->LastAccessTime.ToString()));listBox1->Items->Add(String::Concat(Last Write Time = , pFileProps->LastWriteTime.ToString()));listBox1->Items->Add(String::Concat(Size = , pFileProps->Length.ToString()));

// This shows you how to obtain a list of disk drivers.listBox1->Items->Clear();cli::array<String^>^ drives = Directory::GetLogicalDrives();int numDrives = drives->Length;for(int i=0; i<numDrives; i++){    listBox1->Items->Add(drives[i]);}

// This code obtains a list of folders. This example uses the Windows folder.listBox1->Items->Clear();cli::array<String^>^ dirs = Directory::GetDirectories(windir);int numDirs = dirs->Length;for(int i=0; i<numDirs; i++){    listBox1->Items->Add(dirs[i]);}

// This code obtains a list of files. This example uses the Windows folder.listBox1->Items->Clear();cli::array<String^>^ files = Directory::GetFiles(windir);int numFiles = files->Length;for(int i=0; i<numFiles; i++){    listBox1->Items->Add(files[i]);}

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Complete code sample

// Form1.h#pragma oncenamespace KB950617    using namespace System;    using namespace System::ComponentModel;    using namespace System::Collections;    using namespace System::Windows::Forms;    using namespace System::Data;    using namespace System::Drawing;    using namespace System::IO;    public ref class Form1 : public System::Windows::Forms::Form    {    private:        String^ windir;    public:        Form1(void)        {            InitializeComponent();            windir = System::Environment::GetEnvironmentVariable(windir);        }    protected:        ~Form1()        {            if (components)            {                delete components;            }        }    private: System::Windows::Forms::ListBox^  listBox1;    private: System::Windows::Forms::Button^  button1;    private: System::Windows::Forms::Button^  button2;    private: System::Windows::Forms::Button^  button3;    private: System::Windows::Forms::Button^  button4;    private: System::Windows::Forms::Button^  button5;    private: System::Windows::Forms::Button^  button6;    private:        System::ComponentModel::Container ^components;#pragma region Windows Form Designer generated code        void InitializeComponent(void)        {            this->listBox1 = (gcnew System::Windows::Forms::ListBox());            this->button1 = (gcnew System::Windows::Forms::Button());            this->button2 = (gcnew System::Windows::Forms::Button());            this->button3 = (gcnew System::Windows::Forms::Button());            this->button4 = (gcnew System::Windows::Forms::Button());            this->button5 = (gcnew System::Windows::Forms::Button());            this->button6 = (gcnew System::Windows::Forms::Button());            this->SuspendLayout();            // listBox1            this->listBox1->FormattingEnabled = true;            this->listBox1->Location = System::Drawing::Point(24, 24);            this->listBox1->Name = LlistBox1;            this->listBox1->Size = System::Drawing::Size(450, 199);            this->listBox1->TabIndex = 0;            // button1            this->button1->Location = System::Drawing::Point(500, 32);            this->button1->Name = Lbutton1;            this->button1->Size = System::Drawing::Size(112, 23);            this->button1->TabIndex = 1;            this->button1->Text = LRead Text File;            this->button1->UseVisualStyleBackColor = true;            this->button1->Click += gcnew System::EventHandler(this, &Form1::button1_Click);            // button2            this->button2->Location = System::Drawing::Point(500, 64);            this->button2->Name = Lbutton2;            this->button2->Size = System::Drawing::Size(112, 23);            this->button2->TabIndex = 2;            this->button2->Text = LWrite Text File;            this->button2->UseVisualStyleBackColor = true;            this->button2->Click += gcnew System::EventHandler(this, &Form1::button2_Click);            // button3            this->button3->Location = System::Drawing::Point(500, 96);            this->button3->Name = Lbutton3;            this->button3->Size = System::Drawing::Size(112, 23);            this->button3->TabIndex = 3;            this->button3->Text = LView File Information;            this->button3->UseVisualStyleBackColor = true;            this->button3->Click += gcnew System::EventHandler(this, &Form1::button3_Click);            // button4            this->button4->Location = System::Drawing::Point(500, 128);            this->button4->Name = Lbutton4;            this->button4->Size = System::Drawing::Size(112, 23);            this->button4->TabIndex = 4;            this->button4->Text = LList Drives;            this->button4->UseVisualStyleBackColor = true;            this->button4->Click += gcnew System::EventHandler(this, &Form1::button4_Click);            // button5            this->button5->Location = System::Drawing::Point(500, 160);            this->button5->Name = Lbutton5;            this->button5->Size = System::Drawing::Size(112, 23);            this->button5->TabIndex = 5;            this->button5->Text = LList Subfolders;            this->button5->UseVisualStyleBackColor = true;            this->button5->Click += gcnew System::EventHandler(this, &Form1::button5_Click);            // button6            this->button6->Location = System::Drawing::Point(500, 192);            this->button6->Name = Lbutton6;            this->button6->Size = System::Drawing::Size(112, 23);            this->button6->TabIndex = 6;            this->button6->Text = LList Files;            this->button6->UseVisualStyleBackColor = true;            this->button6->Click += gcnew System::EventHandler(this, &Form1::button6_Click);            // Form1            this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);            this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;            this->ClientSize = System::Drawing::Size(692, 286);            this->Controls->Add(this->button6);            this->Controls->Add(this->button5);            this->Controls->Add(this->button4);            this->Controls->Add(this->button3);            this->Controls->Add(this->button2);            this->Controls->Add(this->button1);            this->Controls->Add(this->listBox1);            this->Name = LForm1;            this->Text = LForm1;            this->ResumeLayout(false);        }#pragma endregion    private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {                 					// How to read a text file:					// Use try...catch to deal with a 0-byte file or a non-existent file.					listBox1->Items->Clear();					try {						StreamReader^ reader = gcnew StreamReader(c:  mytest.txt);						do						{							listBox1->Items->Add(reader->ReadLine());						}						while(reader->Peek() != -1);					}					catch(FileNotFoundException^ ex)					{						listBox1->Items->Add(ex);					}					catch(System::Exception^ e)					{						listBox1->Items->Add(e);					}             }    private: System::Void button2_Click(System::Object^  sender, System::EventArgs^  e) {                 // This demonstrates how to create and to write to a text file.                 StreamWriter^ pwriter = gcnew StreamWriter(c:  KBTest.txt);                 pwriter->WriteLine(The file was created by using the StreamWriter class.);                 pwriter->Close();                 listBox1->Items->Clear();                 String^ filew = gcnew String(File written to c:  KBTest.txt);                 listBox1->Items->Add(filew);             }    private: System::Void button3_Click(System::Object^  sender, System::EventArgs^  e) {                 // This code retrieves file properties. The example uses Notepad.exe.                 listBox1->Items->Clear();                 String^ testfile = String::Concat(windir,  notepad.exe);                 FileInfo^ pFileProps = gcnew FileInfo(testfile);                 listBox1->Items->Add(String::Concat(File Name = , pFileProps->FullName));                 listBox1->Items->Add(String::Concat(Creation Time = , pFileProps->CreationTime.ToString()));                 listBox1->Items->Add(String::Concat(Last Access Time = , pFileProps->LastAccessTime.ToString()));                 listBox1->Items->Add(String::Concat(Last Write Time = , pFileProps->LastWriteTime.ToString()));                 listBox1->Items->Add(String::Concat(Size = , pFileProps->Length.ToString()));             }    private: System::Void button4_Click(System::Object^  sender, System::EventArgs^  e) {                 // This demonstrates how to obtain a list of disk drivers.                 listBox1->Items->Clear();                 cli::array<String^>^ drives = Directory::GetLogicalDrives();                 int numDrives = drives->Length;                 for(int i=0; i<numDrives; i++)                 {                     listBox1->Items->Add(drives[i]);                 }             }    private: System::Void button5_Click(System::Object^  sender, System::EventArgs^  e) {                 // This code obtains a list of folders. This example uses the Windows folder.                 listBox1->Items->Clear();                 cli::array<String^>^ dirs = Directory::GetDirectories(windir);                 int numDirs = dirs->Length;                 for(int i=0; i<numDirs; i++)                 {                     listBox1->Items->Add(dirs[i]);                 }             }    private: System::Void button6_Click(System::Object^  sender, System::EventArgs^  e) {                 // This code obtains a list of files. This example uses the Windows folder.                 listBox1->Items->Clear();                 cli::array<String^>^ files = Directory::GetFiles(windir);                 int numFiles = files->Length;                 for(int i=0; i<numFiles; i++)                 {                     listBox1->Items->Add(files[i]);                 }             }    };}// KB950617.cpp#include stdafx.h#include Form1.husing namespace KB950617;[STAThreadAttribute]int main(array<System::String ^> ^args){    // Enable Windows XP visual effects before any controls are created.    Application::EnableVisualStyles();    Application::SetCompatibleTextRenderingDefault(false);     // Create the main window and run the program.    Application::Run(gcnew Form1());    return 0;}

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For more information about Visual C++ .NET, visit the following Microsoft Usenet newsgroup:

For more information about how to create Windows forms in Managed Extensions for C++, see the ManagedCWinFormWiz sample in Visual Studio .NET Help.

For more information about ECMA C++/CLI, visit the following Microsoft Developer Network (MSDN) Web site:

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