Check if string contains one value or another, syntax error?

Question

I'm coming from a javascript backend to Python and I'm running into a basic but confusing problem

I have a string that can contain a value of either 'left', 'center', or 'right'. I'm trying to test if the variable contains either 'left' or 'right'.

In js its easy:

if( str === 'left' || str === 'right' ){}

However, in python I get a syntax error with this:

if str == 'left' || str == 'right':

Why doesn't this work, and what's the right syntax?

Answer 1

调用Python的逻辑OR运算符or.没有||.

if string == 'left' or string == 'right':
##                  ^^

顺便说一句,在Python中,这种测试通常写成:

if string in ('left', 'right'):

## in Python ?3.1, also possible with set literal
## if string in {'left', 'right'}:

另请注意,这str是 Python中的内置函数.您应该避免命名与它们冲突的变量.