作用域比较奇怪，一般的全局变量是不能在函数中使用的，不过代码块对作用域没有影响。 另外，参数定义时不能指定类型，除非它是个对象；返回值也不能指定（array似乎是可以的）。
<?php # function name does not case sensitive, but variable name does // function plus(integer $a, integer $b) { <-- WRONG!!! // here integer should be a class function plus($a,$b) { return $a+$b; } function mul($a, $b) { return $a*$b; }?>#!/usr/bin/php<?php // if head.inc was not be found, require() will cause a fatal error, but include() will // cause a warning // use require_once/include_once to avoid from include a file more than one time require_once('head.inc'); echo plus(3,4)." "; echo mul(3,4)." "; echo "------- "; # scope # P.S. code block {} does nothing about scope $x=3; function a() { echo $x." "; // $x is a global variable, // but it non-visible here // except $x is a super global variable } a(); echo $x." "; # make a variable to be global function b() { global $y; // export $y to be global $y=4; // assigned after global declaration echo "$y "; } b(); echo "$y "; # default value function c($z=5) { echo "$z "; } c(); c(6);?>
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