PHP：为什么用!! $ var而不是（boolean）$ var进行类型转换？

Question

Both of these will ensure than $var is a boolean value, but the latter seems more clear. The double exclamation mark (!!) is shorter to type but less clear, and more likely to cause confusion. Not to mention hard to run a search on to get answers.

The double exclamation mark is something I've only heard of in JavaScript, which doesn't have boolean typecasting. Is it normal to see it used in PHP as well?

Answer 1

Neither of those is common in PHP because they're unnecessary.

If you can do !!, you can just as well use it where a boolean expression is necessary (while, if, &&, etc.).