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whille loop in Python
what is the difference between these two codes? i = 1 while i <= 5: print(i) i += 1 print("finish") ---> 1 2 3 4 5 finished i = 1 while i <= 5: i += 1 print(i) print("finish") ---> 2 3 4 5 6 finished why in first one 6 is not printed though we wrote <=5. so then 5 can be i, too. we should have another 5 + 1 that produces 6 and why in the second one 6 is written though we limited it saying <=5? I am really confused
3 Respostas
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The difference is the order between the increment and the output.
The loops run from 1 to 5. In the last iteration, i is incremented to 6, so the loop exits.
In the first one, it prints 5, increments to 6, then exits.
In the second one, it increments to 6, prints 6, then exits.
The while exit condition is tested right before each iteration, not in the code block inside the loop.
0
In first case you first check i and after print i
In secon case you first increase i and after print i
0
Best to visualise what is happening in both instances so from i=5
Loop 1:
Is i <= 5? Yes
Print value {5}
i = 6
Is i <= 5? No
Print finished
Loop 2:
Is i <= 5? Yes
i = 6
Print value {6}
Is i <= 5? No
Print finished
This is also the reason that the second loop starts at 2 instead of 1 as i is incremented before the value is printed to the console.
Hope this helps.