Why is this while statement looping infinitely?

Question

I am using Python 2.7 in Windows PowerShell.

def loop(loop):
    i = 0
    numbers = []
    while i < loop:
        print "At the top i is %d" % i
        numbers.append(i)

        i += 1
        print "Numbers now: ", numbers
        print "At the bottom i is %d" % i



value = raw_input("Choose the loop value:\n>")
print value
loop(value)

When I enter 6 as the input for value , loop() turns into an infinite loop.

Any idea what is going wrong?

Answer 1

The result of your raw_input , the variable value (passed to loop in your function) is a string. You are comparing this to i , an integer. In Python 2.x, all integers are less than all strings, so i < loop is always true no matter how big i gets.

Convert your input to an integer to make the comparison work:

value = int(raw_input("Choose the loop value:\n>"))

(And I'd also suggest not naming your function's argument the same as the function itself; it's just confusing.)

Answer 2

You have to put your raw_input in int() .

replace:

 value = raw_input("Choose the loop value:\n>")

on:

 value = int(raw_input("Choose the loop value:\n>"))

OR you can just change:

while i < loop:

to

while i < int(loop):

Answer 3

我确定您实际上正在运行loop（'6'）而不是loop（6）。

Answer 4

because value is a string

you should call your function like this

loop(int(value))