[Solved] This Ruby code tries to open a file for reading and writing:File.open('data.txt', 'r') do |f| f.puts 'New line' endWhat is the problem here? | Ruby

Ruby - File IO

This Ruby code tries to open a file for reading and writing:

File.open('data.txt', 'r') do |f|
  f.puts 'New line'
end

What is the problem here?

AFile opened in 'r' mode truncates file

BFile opened in 'r' mode cannot write, causes error

CFile opened in 'r' mode appends data

DNo problem, code works fine

Step-by-Step Solution

Solution:

Step 1: Check 'r' mode capabilities
'r' mode opens file for reading only, no writing allowed.
Step 2: Writing with 'puts' causes error
Calling 'puts' on file opened in 'r' mode raises an IOError because writing is not permitted.
Final Answer:
File opened in 'r' mode cannot write, causes error -> Option B
Quick Check:
'r' mode is read-only, writing causes error = B [OK]

Quick Trick: 'r' mode forbids writing, use 'r+' for read/write [OK]

Common Mistakes:

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