File.read for entire content in Ruby - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of reading a file with File.read?

Given a file named example.txt containing the text Hello, Ruby!, what will the following code output?

Ruby

content = File.read('example.txt')
puts content

A Hello, Ruby!

B File.read

C nil

D An error because File.read needs a block

💡 Hint

File.read reads the whole file content as a string.

File.read returns the entire content of the file as a string. Here, it reads 'Hello, Ruby!' and prints it.

🧠 Conceptual

intermediate

What does File.read return if the file is empty?

If you use File.read('empty.txt') on an empty file, what will be the returned value?

A An empty string ""

B nil

C 0

D Raises an error

💡 Hint

Think about what reading an empty file means as text.

Reading an empty file returns an empty string, not nil or an error.

🔧 Debug

advanced

Why does this code raise an error?

This code tries to read a file but raises an error. What is the cause?

Ruby

content = File.read()
puts content

A File.read returns nil and puts fails

B Missing filename argument causes ArgumentError

C File.read needs a block, so error is raised

D File.read cannot read text files

💡 Hint

Check the method signature for File.read.

File.read requires a filename argument. Calling it without arguments raises ArgumentError.

❓ Predict Output

advanced

What is the output when reading a file with encoding specified?

Given a file utf8.txt containing UTF-8 text, what does this code output?

Ruby

content = File.read('utf8.txt', encoding: 'UTF-8')
puts content.encoding.name

A UTF-16

B ASCII-8BIT

C UTF-8

D EncodingError

💡 Hint

File.read can take encoding option to read file with specific encoding.

Specifying encoding: 'UTF-8' makes File.read return a string with UTF-8 encoding.

🧠 Conceptual

expert

How many bytes does File.read return when reading a binary file?

If you read a binary file with File.read('image.png', mode: 'rb'), what is the type and length of the returned object?

A A File object opened in binary mode

B An Array of bytes, length equals file size in bytes

C A String with UTF-8 encoding, length equals number of characters

D A String containing all bytes of the file, length equals file size in bytes

💡 Hint

File.read returns a string even in binary mode, but bytes are raw data.

File.read returns a String containing all bytes. The length is the file size in bytes. Encoding is ASCII-8BIT in binary mode.