Python - File Reading and Writing Strategies
Why is reading a large file line by line using a for loop over the file object more memory efficient than using readlines()?
Why is reading a large file line by line using a for loop over the file object more memory efficient than using readlines()?
hard📝 Conceptual Q10 of 15
Step-by-Step Solution
Solution:
Step 1: Understand readlines() behavior
readlines()reads all lines into a list, loading the entire file into memory.Step 2: Understand for loop over file object
Iterating over the file object reads one line at a time, using less memory.Final Answer:
Because readlines() loads all lines into memory at once -> Option AQuick Check:
Memory use difference = C [OK]
Quick Trick: For loop reads lines lazily; readlines() loads all [OK]
Common Mistakes:
- Thinking readlines() reads one line
- Believing for loop reads whole file
- Confusing bytes and strings
- Assuming automatic conversion
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