定义了常量,还要获取常量的值,除了通过我们指定的常量名直接获取外,还可以通过 constant() 函数来获取:


<?php 
	define("PI1",3.141592653);
	define("PI2",3.142);
	$p = "PI2";
	$var_pi1 = PI1;
	echo $var_pi1;
	echo "\n";
	$var_pi2 = constant($p);
	echo $var_pi2;
?>