File.write for writing in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to write the string 'Hello' to a file named 'greeting.txt'.

Ruby

File.[1]('greeting.txt', 'Hello')

Drag options to blanks, or click blank then click option'

Awrite

Bread

Copen

Dclose

Attempts:

3 left

💡 Hint

Common Mistakes

Using File.read instead of File.write

Using File.open without a block

Trying to use File.close directly

The File.write method writes the given string to the specified file.

2fill in blank

medium

Complete the code to write 'Ruby is fun!' to a file named 'fun.txt'.

Ruby

File.[1]('fun.txt', 'Ruby is fun!')

Drag options to blanks, or click blank then click option'

Aread

Bappend

Cwrite

Ddelete

Attempts:

3 left

💡 Hint

Common Mistakes

Using File.append which adds instead of overwriting

Using File.read which only reads files

Using File.delete which removes files

File.write writes the string to the file, replacing any existing content.

3fill in blank

hard

Fix the error in the code to write 'Data' to 'data.txt'.

Ruby

File.[1]('data.txt', 'Data')

Drag options to blanks, or click blank then click option'

Aread

Bwrite

Cgets

Dputs

Attempts:

3 left

💡 Hint

Common Mistakes

Using File.read which only reads files

Using File.puts which does not exist

Using File.gets which reads input

File.write is the correct method to write data to a file. puts and gets are for console input/output.

4fill in blank

hard

Fill both blanks to write the string length of 'hello' to 'length.txt'.

Ruby

File.[1]('length.txt', 'hello'.[2].to_s)

Drag options to blanks, or click blank then click option'

Awrite

Bread

Clength

Dsize

Attempts:

3 left

💡 Hint

Common Mistakes

Using File.read instead of File.write

Using length instead of size (both work but only one is correct here)

Confusing read and write methods

File.write writes to the file, and size returns the length of the string.

5fill in blank

hard

Fill all three blanks to write uppercase words longer than 3 letters from the list to 'output.txt'.

Ruby

words = ['cat', 'elephant', 'dog', 'lion']\nFile.write('output.txt', words.select { |word| word.[2] [3] 3 }.map { |word| word.[1] }.join("\n"))

Drag options to blanks, or click blank then click option'

Aupcase

Blength

C>

Ddowncase

Attempts:

3 left

💡 Hint

Common Mistakes

Using downcase instead of upcase

Using < instead of > for length comparison

Using read instead of write for file output

upcase converts words to uppercase, length gets the word length, and > checks if length is greater than 3.

Practice

1. What does the Ruby method File.write do by default when writing to a file?

easy

A. It creates the file if it doesn't exist and overwrites existing content.

B. It appends new content to the end of the file without changing existing content.

C. It only reads the file content without modifying it.

D. It deletes the file before writing new content.

Solution

1. Step 1: Understand File.write default behavior

   By default, File.write creates the file if it does not exist.

2. Step 2: Check how it handles existing files

   If the file exists, it overwrites the entire content with the new data.

3. Final Answer:

   It creates the file if it doesn't exist and overwrites existing content. -> Option A

4. Quick Check:

   File.write overwrites by default = A [OK]

Hint: Remember: File.write overwrites unless mode is changed [OK]

Common Mistakes:

• Thinking File.write appends by default
• Assuming File.write only reads files
• Believing File.write deletes files before writing

2. Which of the following is the correct syntax to write the string "Hello" to a file named "greet.txt" using File.write in Ruby?

easy

A. File.write("greet.txt") { "Hello" }

B. File.write("Hello", "greet.txt")

C. File.write("greet.txt", "Hello")

D. File.write("greet.txt" => "Hello")

Solution

1. Step 1: Identify File.write parameters

   The first argument is the filename, the second is the content string.

2. Step 2: Match correct syntax

   File.write("greet.txt", "Hello") correctly uses File.write("greet.txt", "Hello").

3. Final Answer:

   File.write("greet.txt", "Hello") -> Option C

4. Quick Check:

   File.write(filename, content) = C [OK]

Hint: Filename first, content second in File.write [OK]

Common Mistakes:

• Swapping filename and content arguments
• Using block syntax incorrectly
• Passing a hash instead of arguments

3. What will be the content of the file "data.txt" after running this Ruby code?

File.write("data.txt", "Line 1\n")
File.write("data.txt", "Line 2\n")

medium

A. Line 2\n

B. Line 1\nLine 2\n

C. Line 1\n

D. Line 1\n\nLine 2\n

Solution

1. Step 1: Analyze first File.write call

   It writes "Line 1\n" to "data.txt", creating or overwriting the file.

2. Step 2: Analyze second File.write call

   It overwrites the entire file content with "Line 2\n" because File.write overwrites by default.

3. Final Answer:

   Line 2\n -> Option A

4. Quick Check:

   File.write overwrites, so last write stays = B [OK]

Hint: Each File.write overwrites unless mode 'a' is set [OK]

Common Mistakes:

• Assuming File.write appends by default
• Expecting both lines to be in the file
• Confusing newline characters with extra lines

4. The following Ruby code is intended to append "More text" to the file "notes.txt". What is the error?

File.write("notes.txt", "More text")

medium

A. The filename should be a symbol, not a string.

B. File.write overwrites instead of appending; mode 'a' is missing.

C. The string "More text" must be inside single quotes.

D. File.write cannot write strings, only bytes.

Solution

1. Step 1: Understand File.write default mode

   By default, File.write overwrites the file content.

2. Step 2: Identify how to append

   To append, you must specify mode: File.write("notes.txt", "More text", mode: "a").

3. Final Answer:

   File.write overwrites instead of appending; mode 'a' is missing. -> Option B

4. Quick Check:

   Append needs mode 'a' = A [OK]

Hint: Use mode: 'a' to append with File.write [OK]

Common Mistakes:

• Not specifying mode to append
• Using symbols instead of strings for filename
• Thinking quotes style affects writing
• Believing File.write can't write strings

5. You want to write multiple lines to a file "log.txt" without overwriting existing content. Which Ruby code correctly appends these lines using File.write?

hard

A. File.write("log.txt", "First line\nSecond line\n", append: true)

B. File.write("log.txt", "First line\nSecond line\n")

C. File.write("log.txt", "First line\nSecond line\n", mode: "w")

D. File.write("log.txt", "First line\nSecond line\n", mode: "a")

Solution

1. Step 1: Identify how to append with File.write

   Appending requires mode set to "a" (append mode).

2. Step 2: Check options for correct syntax

   File.write("log.txt", "First line\nSecond line\n", mode: "a") uses mode: "a" correctly to append multiple lines.

3. Final Answer:

   File.write("log.txt", "First line\nSecond line\n", mode: "a") -> Option D

4. Quick Check:

   Append mode is 'a' in File.write = D [OK]

Hint: Use mode: 'a' to append multiple lines safely [OK]

Common Mistakes:

• Omitting mode for append
• Using mode 'w' which overwrites
• Using invalid option 'append: true'