Python三元运算符行为

Question

when I evaluate the following operation

0 if True else 1 + 1 if False else 1

it evaluates to 0 however when I write with brackets like

( 0 if True else 1 ) + ( 0 if False else 1 )

it evaluates correctly to 1 , what is happening in the first case.

Answer 1

0 if True else 1 + 1 if False else 1

is actually:

(0) if (True) else ((1 + 1) if (False) else (1))

which is definitely differs from what you want:

((0) if (True) else (1)) + ((1) if (False) else (1))

Answer 2

as ternary operator is read from left to right and + has lower precedence than conditional operators. So, these two are equivalent:

>>> 0 if True else 1 + 1 if False else 1
0
>>> 0 if True else ( (1 + 1) if False else 1)
0

Answer 3

三元运算符看起来像“条件？如果为true的值：如果为false的值”，但是python似乎不支持它，但是我们可以使用if-else进行替换。stype类似于“条件if（b_1）else b_2 ，因此可以依赖它进行匹配。如果b_1为True，则为condition；如果b_2为True，则为b_2。