File Handling

Reading Files:

Reading files are very simple in Ruby than other languages.

Reading Files in Ruby

This is the content of the file named sample.txt. Now, we are going to read the contents of this file.

Reading Files in Ruby

This small piece of code reads the contents of any file. You might be confused that there is no statement about the file name. We can specify the file name in the Command Prompt while running the program.

We run by: ruby files.rb sample.txt

Here’s the output:

Reading Files in Ruby

This is one method of reading the file. We could also read the file by specifying the name of the file in the program. Like this:

Reading Files in Ruby

Here, we are opening the file using open method. Variable file acts as a file handler here. So, for each line we are calling the gets method using the variable file and storing it in the variable line and printed using puts method.

The output of the program is :

Reading Files in Ruby


Writing Files:

We have to create a File object using new method for reading data from files or writing data to files.

Writing Files in Ruby

Here fil is the file object which is created using the new method. The new method has two parameters, the first parameter is the name of the file and the second parameter is the mode. “w” represents write mode to a file. We are using the file object fil with the print and puts method to literally write to the file.

When we are finished, we should always close the file. It is a good practice to always close the file when done. If we don’t close the file, the file maybe corrupted when we try to open it later sometimes. The data printed using print and puts method are stored in the buffer, the buffer is flushed when we close the file.

The output of the program is :

Writing Files in Ruby

Actually, nothing happens when we execute the program. But when we view the file, the content is written in the file. Here is another example,

Writing Files in Ruby

Writing Files in Ruby