为什么变量声明在php，perl等脚本语言中如此简单，而在Java，C等中却没有？

Question

In php/perl we can simply say $a='hi" and then $a=1 without needing to declare its type. But there are type casting errors in java for the same.

Why this difference?

Answer 1

PHP is dynamically typed, while Java and C are statically typed.

With static typing, type checking can be done at compile time and this can catch many errors, so it's not necessarily a bad thing. This also allows them to be much faster than dynamic languages.

See: http://en.wikipedia.org/wiki/Type_system