`while y < x` loop never ends

I'm trying out Python, and, in my very tired state, can't seem to find the problem with the code below:

import sys

def printNum(x):
    y = 0
    while y < x:
        print "Number: ", y
        y = y + 1

printNum(sys.argv[1])

So, I'm trying to get it to print out y x times. x is passed as a parameter. The loop never ends开发者_开发知识库 and I don't know why!

Ouch!

Your problem is that sys.argv[1] gives you a str, and a str is always greater than an int.

For example:

>>> '2' < 1
False
>>> '1' < 2
False

So what you'll need to do is change your last line to

printNum(int(sys.argv[1]))

Currently this code will paste a str into printNum, but printNum treats the input (x) like an int. To fix this, convert the input to an int:

printNum(int(sys.argv[1]))

The x value that you get as a command line parameter is passed in as a string, not as an integer. All integers are treated as being less than all strings:

>>> 1 < "2"
True
>>> 3 < "2"
True
>>> 1000000 < "2"
True

...so your loop will never end.

try:

 printNum(int(sys.argv[1]))