Reading and writing files using File methods

**ArekBulski** · 09-03-2009 05:10 AM

Hello members! This tutorial is a bit nostalgic to me. Here is one of the few reasons why I am into .NET programming so much, instead of Java or C++ for example. I want to show you the File class, which is a small thing but makes my day nice.

We need a sample file...

For a start, we need some sample file to read it. I created a new console application. Then I selected the Program.cs file in the Solution Explorer panel, and switched to Properties panel. There is a property called Copy to Output Directory. I changed it to have a copy of this file in the Bin\Release\ folder. Viola, a sample file to read it, right up.

Reading and writing with File class

Let's start with some simple code, the goal is to read a file. After writing "File" press Ctrl+. and click to import the System.IO namespace. Then you just need one line of code, which one, depends on your needs.

Code:


byte[] asBytes = File.ReadAllBytes("Program.cs");



string asString = File.ReadAllText("Program.cs");



string[] asLines = File.ReadAllLines("Program.cs");

Displaying the file contents

Here are screenshots of looking up the variables that contain what was read. Look at them, and decide which one of them is useful for you at the moment.

Reading and writing files using File methods-bytes.jpg

Reading and writing files using File methods-string.jpg

Reading and writing files using File methods-lines.jpg

Writing data back to files

This is again what I like in .NET the most. All writing can be done in one line of code. Unless those files weight in gigabytes, your pc will not run out of memory. You can read for example setting files, or code (.cs) files this way without worrying that it will eat up your memory.

Depending on which variable or data type you want to write, you can pick one of the lines.

Code:

File.WriteAllBytes("Saved as bytes.cs", asBytes);

File.WriteAllText("Saved as string.cs", asString);

File.WriteAllLines("Saved as lines.cs", asLines);

Leave comments and enjoy your day

I hope this tutorial will be helpful or at least make your day a little bit less of writing code and more of enjoying your day. Comments and +rep are always appreciated.