How to: Read a Text File (C++/CLI)

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The latest version of this topic can be found at How to: Read a Text File (C++/CLI).

The following code example demonstrates how to open and read a text file one line at a time, by using the StreamReader class that's defined in the System.IO namespace. An instance of this class is used to open a text file and then the StreamReader.ReadLine method is used to retrieve each line.

This code example reads a file that's named textfile.txt and contains text. For information about this kind of file, see How to: Write a Text File (C++/CLI).

Example

// text_read.cpp  
// compile with: /clr  
#using<system.dll>  
using namespace System;  
using namespace System::IO;  
  
int main()  
{  
   String^ fileName = "textfile.txt";  
   try   
   {  
      Console::WriteLine("trying to open file {0}...", fileName);  
      StreamReader^ din = File::OpenText(fileName);  
  
      String^ str;  
      int count = 0;  
      while ((str = din->ReadLine()) != nullptr)   
      {  
         count++;  
         Console::WriteLine("line {0}: {1}", count, str );  
      }  
   }  
   catch (Exception^ e)  
   {  
      if (dynamic_cast<FileNotFoundException^>(e))  
         Console::WriteLine("file '{0}' not found", fileName);  
      else  
         Console::WriteLine("problem reading file '{0}'", fileName);  
   }  
  
   return 0;  
}  

See Also

File and Stream I-O
.NET Programming with C++/CLI (Visual C++)