That one afternoon I finally understood loops after 3 failed tutorials

I spent all Tuesday trying to wrap my head around for loops in Python and kept getting infinite loops that crashed my browser. Then a guy on Discord told me to print the loop variable each iteration, and it suddenly clicked why my code was stuck. Has anyone else had a weird simple trick that made a hard concept just fall into place?

3 comments

3 Comments

aaronsullivan1mo ago

I had a similar moment with while loops in JavaScript back in 2022. I kept getting infinite loops because I forgot to increment my counter variable inside the loop body. A coworker told me to put a console.log right before the closing brace and watch what the counter was doing each pass through. That one line showed me I was updating the wrong variable entirely, and it fixed the problem in about thirty seconds. Sometimes the simplest debug step is just watching the numbers change in real time.

wendy8201mo ago

Printing the loop variable is genius, that totally would have saved me hours.

shane_park921mo ago

The loop variable trick is decent for sure but it has a flaw. If your code has nested loops, printing the wrong variable will give you garbage data that looks right but isn't. I wasted two days on a sorting algorithm because I was printing i instead of j in a double loop. Double check which loop you're actually debugging before you start.