Strange logic with bool

Question

Hello, I can't understand one thing with logic in python. Here is the code:

maxCounter = 1500
localCounter = 0

while True:
   print str(localCounter) + ' >= ' + str(maxCounter)
   print localCounter >= maxCounter

   if localCounter >= maxCounter:
      break

   localCounter += 30

And the result output:

...
1440 >= 1500
False
1470 >= 1500
False
1500 >= 1500
False
1530 >= 1500
False
1560 >= 1500
False
...

And I have infinity cycle there. Why?

---

topPos = someClass.get_element_pos('element')
scrolledHeight = 0

while True:
    print str(scrolledHeight) + ' >= ' + str(topPos)
    print scrolledHeight >= topPos
    if scrolledHeight >= topPos:
        print 'break'
        break

    someClass.run_javascript("window.scrollBy(0, 30)")
    scrolledHeight += 30
    print scrolledHeight

    time.sleep(0.1)

Answer 1

To fix your code try this:

topPos = int(someClass.get_element_pos('element'))

Why?

When I copy and paste your original code I get this:

...
1440 >= 1500
False
1470 >= 1500
False
1500 >= 1500
True

One small change that I can find to make to your code that reproduces the behaviour you are seeing is to change the first line to this:

maxCounter = '1500'  # string instead of integer

After making this change I can also see the output you get:

1410 >= 1500
False
1440 >= 1500
False
1470 >= 1500
False
1500 >= 1500
False
1530 >= 1500
False
etc..

Answer 2

The problem seems to be at this line:

topPos = someClass.get_element_pos('element')

This is likely to assign a string to topPos, instead of a numeric variable. You need to convert this string to a numeric variable so you can do a numeric comparison against it.

topPos = int(someClass.get_element_pos('element'))

Otherwise, e.g. in CPython implementation of v2.7, any int is always going to compare less than any string.

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