Multiple conditions If statement python doesn't work

Question

I can't find what's wrong but my next code doesn't work:

if finalsum!=0 and (x[0]!='-' or x[0]!='+'):

Do something...

I need to add 2 more conditions If I try only one AND, the code works, if I add the OR, nothing happens.

Also I've tried few more ways to write it and it doesn't work as well.

@gspr answer is good enough. Unless you want to add more details that clarify your problem in another way — Shadi Naif
– Shadi Naif, Commented Jul 21, 2020 at 12:18

gspr · Accepted Answer · 2020-07-21 12:04:39Z

4

The x[0]!='-' or x[0]!='+' condition is vacuous. It is always true.

If x[0] is anything other than '-', then first part of the condition is true, so the whole condition is true. If x[0] is anything other than '+', such as for example '-', then the second part of the condition is true, so the whole condition is true. Thus the whole condition is true nomatter the value of x[0].

edited Jul 21, 2020 at 12:04

answered Jul 21, 2020 at 11:58

gspr

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