CODEWITHSUNDEEP
pythonloopswhile-loop
illymarev
illymarev

Reputation: 256

Incorrect while loop

I want the loop to stop when one of the numbers reaches 4 million. But it's working incorrectly. Could someone help me?

number1=0
number2=1
while number1<(4000000):
    number1+=number2
    number2+=number1
    print(number1,number2)

Here are the numbers I get:

1 2
3 5
8 13
21 34
55 89
144 233
377 610
987 1597
2584 4181
6765 10946
17711 28657
46368 75025
121393 196418
317811 514229
832040 1346269
2178309 3524578
5702887 9227465

Upvotes: 1

Views: 367

Answers (3)

I159
I159

Reputation: 31199

There are a lot of options to do it. The main problem is the logical sequence:

check -> increment -> print

Whenever you increment after check, the printed value is greater than the value used for comparison.

And another option in addition (not the best one):

number1 = 0
number2 = 1
while True:
    number1 += number2
    number2 += number1
    if number1 <= (4000000):
        print(number1, number2)
    else:
        break

You should use <= instead of < for a case when number1 exactly equals 4000000. With <, it will go to infinity loop.

Upvotes: 0

DarknessPlusPlus
DarknessPlusPlus

Reputation: 563

Be a pro about it. No need to restructure your code. Just skip the last iteration. This basically what we want to do.

number1=0
number2=1

while number1<(4000000):
    print(number1,number2)
    number1+=number2
    number2+=number1

Upvotes: 0

David Montgomery
David Montgomery

Reputation: 473

It is working correctly - when number1 reaches 4 million it stops. If the issue is that numbers above 4 million are printed you could break an infinite loop instead:

while True:
    number1+=number2
    number2+=number1
    if number1 > 4000000:
        break
    print(number1, number2)

Upvotes: 4

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