Ruby - File IO
You want to read a file and count how many lines contain the word 'error'. Which Ruby code correctly does this using file handling?
You want to read a file and count how many lines contain the word 'error'. Which Ruby code correctly does this using file handling?
hard📝 Application Q15 of 15
Step-by-Step Solution
Solution:
Step 1: Identify correct file mode and iteration
count = 0 File.open('log.txt', 'r') do |file| file.each_line do |line| count += 1 if line.include?('error') end end puts count opens file in 'r' mode and uses each_line with block, counting lines with 'error'.Step 2: Check other options for errors
count = 0 file = File.open('log.txt', 'w') file.each_line do |line| count += 1 if line.include?('error') end file.close puts count opens file in 'w' (write) mode, wrong for reading; count = 0 File.read('log.txt').each do |line| count += 1 if line.include?('error') end puts count uses File.read but does not handle string properly; count = 0 File.open('log.txt') do |file| file.read.each do |line| count += 1 if line.include?('error') end end puts count misses mode argument in File.open.Final Answer:
count = 0 File.open('log.txt', 'r') do |file| file.each_line do |line| count += 1 if line.include?('error') end end puts count -> Option BQuick Check:
Open file read + each_line + count lines with 'error' [OK]
Quick Trick: Open file in 'r' mode and use each_line to count matches [OK]
Common Mistakes:
- Opening file in write mode when reading
- Not specifying mode in File.open
- Using File.read without splitting lines
Master "File IO" in Ruby
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