i = true 和 false 在 Ruby 中是真的吗? [英] i = true and false in Ruby is true?

问题描述

我是不是从根本上误解了 Ruby?我已经写了大约 2 年的 Ruby 代码，今天偶然发现了这个......

Am I fundamentally misunderstanding Ruby here? I've been writing Ruby code for about 2 years now and just today stumbled on this...

ruby-1.8.7-p249 > i = true and false
 => false 
ruby-1.8.7-p249 > i
 => true 

有人可以解释一下这里发生了什么吗?我确定它符合规范，但对我来说似乎违反直觉...

Could somebody explain what's going on here please? I'm sure it's to spec, but it just seems counter intuitive to me...

推荐答案

&& 和 and 运算符的优先级不同，=恰好介于两者之间.

The operators && and and have different precedence, and = happens to be in between.

irb(main):006:0> i = true and false
=> false
irb(main):007:0> i
=> true
irb(main):008:0> i = true && false
=> false
irb(main):009:0> i
=> false
irb(main):010:0> 

第一个读作(i = true) and false，第二个读作i = (true && false).

The first is read as (i = true) and false, the second as i = (true && false).

这篇关于i = true 和 false 在 Ruby 中是真的吗?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！