if-statement - Python 语句总是被执行协助

Question

我有以下条件语句：

if (sc == 'Both') and (fc == 'True') or (bc == 'True'):
     do this
if (sc == 'Front') and (fc == 'True'):
     do this
if (sc == 'Back') and (bc == 'True'):
    do this

问题是第二个和第三个子句按预期工作，但是，如果 sc 等于两者并且 fc 和 bc 都为假，则该语句仍然执行，我不知道为什么。

Answer 1

你写了

if ((sc == 'Both') and (fc == 'True')) or (bc == 'True'):
     do this
if (sc == 'Front') and (fc == 'True'):
     do this
if (sc == 'Back') and (bc == 'True'):
    do this

我想你的意思是

#                                     or binds weaker than and so it needs brackets
if (sc == 'Both') and ((fc == 'True') or (bc == 'True')):
     do this
if (sc == 'Front') and (fc == 'True'):
     do this
if (sc == 'Back') and (bc == 'True'):
    do this

您可以and并且or比对数字的任何操作更弱，所以这也是正确的：

if sc == 'Both' and (fc == 'True' or bc == 'True'):
     do this
if sc == 'Front' and fc == 'True':
     do this
if sc == 'Back' and bc == 'True':
    do this