Ruby File Class And Methods

The File class in Ruby is used for handling and manipulating files. Here are some of the most commonly used methods:

1. Creating a New File:

You can create a new file using the new method, which also opens the file:

file = File.new("test.txt", "w")
file.close

In this example, "test.txt" is the filename and "w" is the mode (write). Remember to close the file afterwards with file.close.

2. Opening a File:

The open method can be used to open a file. It also creates a new file if it doesn't exist:

File.open("test.txt", "w") do |file|
  file.puts "Hello, world!"
end

Here, "test.txt" is the filename and "w" is the mode (write). The block is executed with the file object as the parameter, and the file is automatically closed after the block is executed.

3. Reading from a File:

You can read the contents of a file using the read method:

content = File.read("test.txt")
puts content

4. Writing to a File:

You can write to a file using the write method:

File.open("test.txt", "w") do |file|
  file.write "Hello, world!"
end

5. Appending to a File:

You can append to a file using the "a" mode:

File.open("test.txt", "a") do |file|
  file.puts "Hello again, world!"
end

6. Checking if a File Exists:

The exist? method can be used to check if a file exists:

puts File.exist?("test.txt")  # Outputs: true or false

7. Deleting a File:

The delete method can be used to delete a file:

File.delete("test.txt")

8. Renaming a File:

The rename method can be used to rename a file:

File.rename("oldname.txt", "newname.txt")

9. Getting File Size:

The size method can be used to get the size of a file in bytes:

puts File.size("test.txt")

10. Getting File Information:

The stat method returns a File::Stat object, which contains information about the file:

info = File.stat("test.txt")
puts info.size  # File size in bytes
puts info.atime  # Last access time
puts info.mtime  # Last modification time

These are just a few of the most commonly used methods in the File class. There are many more methods for more advanced operations, such as changing file permissions or reading file metadata. For a complete list, refer to the Ruby documentation.

Ruby File open method:
- Description: The File.open method is used to open or create a file, providing a file handle for subsequent operations.
- Code example:
```
file = File.open('example.txt', 'w')
# Perform file operations
file.close
```
Read and write files in Ruby:
- Description: Use File.read and File.write for simple file read and write operations.
- Code example:
```
content = File.read('example.txt')
File.write('output.txt', content)
```
Working with file paths in Ruby:
- Description: Use File.join to safely concatenate file paths.
- Code example:
```
file_path = File.join('path', 'to', 'file.txt')
```
Ruby File read method example:
- Description: The File.read method reads the entire content of a file.
- Code example:
```
content = File.read('example.txt')
puts content
```
Ruby File write method example:
- Description: The File.write method writes content to a file, overwriting existing content.
- Code example:
```
File.write('example.txt', 'Hello, Ruby!')
```
File modes in Ruby File class:
- Description: File modes, such as 'r', 'w', and 'a', determine how files are opened (read, write, append).
- Code example:
```
file = File.open('example.txt', 'r')
```
Checking if a file exists in Ruby:
- Description: Use File.exist? or File.file? to check if a file exists.
- Code example:
```
if File.exist?('example.txt')
  puts 'File exists.'
else
  puts 'File does not exist.'
end
```
File permissions in Ruby:
- Description: File permissions can be set using the File.chmod method.
- Code example:
```
File.chmod(0644, 'example.txt') # Sets read and write permissions for owner
```
Appending to a file in Ruby:
- Description: Use the 'a' mode to open a file for appending.
- Code example:
```
File.open('example.txt', 'a') { |f| f.puts 'Appended content' }
```
Deleting a file with Ruby File class:
- Description: The File.delete method deletes a file.
- Code example:
```
File.delete('example.txt')
```
Listing files in a directory with Ruby:
- Description: Use Dir.entries or Dir.glob to list files in a directory.
- Code example:
```
files = Dir.entries('.')
puts files
```
Ruby File size and properties:
- Description: Use File.size to get the size of a file and File.mtime for the last modification time.
- Code example:
```
size = File.size('example.txt')
mtime = File.mtime('example.txt')
```