如果循环python，在给定范围内的数字

Question

I'm trying to compute this simple expression in python:

if a number is bigger than -1.0 and smaller than 1.0 do something.

I tried this:

if x > '-1.0' and x < '1.0':
    DoSomething

but it turns out that it evaluates only the second part (x < '1.0'). I also tried

if '-1.0' < x < '1.0':
    DoSomething 

but strangely I don't get what I want. Any suggestion please????

Answer 1

You are comparing with strings, not numbers.

if x > -1.0 and x < 1.0:
    pass

Will do the comparison on numbers.

Answer 2

You don't want to put the numbers in quotes - that results in a string comparison, not a numeric comparison. You want

if x > -1.0 and x < 1.0:
    DoSomething

Answer 3

As other answers have mentioned, you need to remove the quotes so that you are comparing with numbers rather than strings.

However, none of those answers used Python's chained comparisons :

if -1.0 < x < 1.0:
    DoSomething 

This is equivalent to if x > -1.0 and x < 1.0 , but more efficient because x is only evaluated once.

Answer 4

这也有效：

if abs(x) < 1.0

Answer 5

What you are doing in that code is comparing x with the string value '-1.0' or '1.0', not the double value. Try the following:

if x > -1.0 and x < 1.0: