如何在具有range（）的循环中使用变量？ （蟒蛇）

Question

I've been searching for quite a while, and I can't seem to find the answer to this. I want to know if you can use variables when using the range() function. For example, I can't get this to work:

l=raw_input('Enter Length.')
#Let's say I enter 9.
l=9
for i in range (0,l):
    #Do something (like append to a list)

Python tells me I cannot use variables when using the range function. Can anybody help me?

Answer 1

Since the user inputs is a string and you need integer values to define the range, you can typecast the input to be a integer value using int method.

>> l=int(raw_input('Enter Length: '))  # python 3: int(input('Enter Length: '))
>> for i in range (0,l):
>>    #Do something (like append to a list)

Answer 2

You ask user to input a number

l = raw_input('Enter Length: ')

But the problem is that entered number will be presented as a string instead of int. So you have to convert string 2 int

l = int(raw_input('Enter Length: '))

If you use Python 2.X you also can optimize your code - instead of range you might use xrange . It works much faster.

for i in xrange (l):
    #Do something (like append to a list)

In Python 3.X xrange was implemented by default

Answer 3

Try this code:

x = int(input("the number you want"))
for i in range(x):