python - If Else 语句、AND OR 逻辑运算和文本文件(使用 Python)

Question

我在 if else 语句中使用 AND 和 OR 时遇到一些问题。这是我的代码:

if subject == 'history' or subject == 'History' and unit == 'WWII' or unit == 'ww2':

有什么想法可以解决这个问题吗？

Answer 1

阅读operator-precedence - 一些运算符比其他运算符绑定(bind)更强 - 要获得所需的逻辑输出，您应该使用 ( ) 来构建逻辑条件。

总结:

Operator                              Description
lambda                                Lambda expression
if – else                             Conditional expression
or                                    Boolean OR
and                                   Boolean AND
not x                                 Boolean NOT
in, not in, is, is not, <, <=, >, >=, !=, ==  Comparisons, including membership tests and identity tests
|                                     Bitwise OR
^                                     Bitwise XOR
&                                     Bitwise AND
<<, >>                                Shifts
+, -                                  Addition and subtraction
*, @, /, //, %                        Multiplication, matrix multiplication, division, floor division, remainder [5]
+x, -x, ~x                            Positive, negative, bitwise NOT
**                                    Exponentiation [6]
await x                               Await expression
x[index], x[index:index], x(arguments...), x.attribute       Subscription, slicing, call, attribute reference
(expressions...), [expressions...], {key: value...}, {expressions...}     Binding or tuple display, list display, dictionary display, set display

操作符越早，它的绑定(bind)就越高。请参阅链接的 doku 以了解订阅上下文