1.引用全局变量
法1
1 <?php
2 $var=0;
3 function test($index)
4 {
5 global $var;
6 $var=$var+1;
7 echo "The ".$index." number is ".$var."<br>";
8 }
9 test(1);
10 test(2)
11 ?>
法2
1 <?php
2 $var=0;
3 function test($index)
4 {
5
6 $GLOBALS["var"]=$GLOBALS["var"]+1;
7 echo "The ".$index." number is ".$GLOBALS["var"]."<br>";
8 }
9 test(1);
10 test(2)
11 ?>
2.定义常量
bool define ( string name, mixed value [, bool case_insensitive] )
name 为常量名，value为常量的值。case_insensitive]为大小写敏感。默认为敏感。例如：
1 <?php
2 define("CONSTANT", "Hello world.");
3 echo CONSTANT; // outputs "Hello world."
4 echo Constant; // outputs "Constant" and issues a notice.
原文：
http://www.cnblogs.com/confach/articles/470492.html