lua 小白问题 a and b or c

[CodeU]

教程上说 的是 a and b or c 就像 c里面的 a?b:c
可是我有点想不通
下面是 例子
a = 1;b= false;c = 2;
c++里 是
d= a?b:c; 结果 毫无疑问 是 d = b;//(false)


lua里是
d = a and b or c ;
-- 先算的是 a and b 因为a 是 true 则返回 b
--[[然后是上面的结果 b or c , 因为b是false 所以返回 c
所以结果 是 d = c ]]
end
上面看起来结果完全不同 这是为什么？

[zuxi]

教程也是人写的，难免有错。 你都用程序来证明了，难道就想不到教程是错的？ 实践就是最好的教程！

[panghuhu250]

这儿(http://lua-users.org/wiki/TernaryOperator)说到a and b or c的用法, 指出:

引用

The main caveat is that if a or c evaluates to true while b or d respectively evaluate to false, then this expression will not behave exactly like the ternary operator. Here, "evaluate to false" means that the value is either false or nil, and "evaluate to true" means not evaluate to false. In the first line above, a and b or c is interpreted as (a and b) or c (because and has higher precedence than or), and if a evaluates to true, then the expression becomes b or c, and if b evaluates to false, then the expression becomes c (not b as you might want).

[七擒关羽]

这里的and or 是指 && ||，我没看到过你提的这种理解

[玄离gg]

如果能够断言a and b or c中的b一定为真，那直接用这种写法不会错 如果b为false,就会出错