PHP 全局变量_PHP教程

<span php><span> = "why"<span><span function><span changename><span> = "what"<span></span>changeName();
</span><span echo> "my name is " . <span> . "<br>"<span>?></span></span></span></span></span></span></span></span>

　　执行代码的结果是：my name is why，而不是执行changename()后显示what。分析原因，这是因为函数体changename内$name变量被缺省设置为局部变量,$name的作用域就是在changename内。于是，修改代码，添加全局变量如下：

<span php><span global> <span><span><span> = "why"<span><span function><span changename><span> = "what"<span></span>changeName();
</span><span echo> "my name is " . <span> . "<br>"<span>?></span></span></span></span></span></span></span></span></span></span></span>

　　注意：

　　定义全局变量后执行的结果仍然为my name is why，这个结果让我吃惊。原来，" 也就是说，当一个函数引用一个外部变量时，可以在函数内通过global来声明该变量，这样该变量就可以在函数中使用了（相当于当作参数传递进来）。那么，再次修改代码：

<span php><span> = "why"<span><span function><span changename><span global> <span><span><span> = "what"<span changename><span echo> "my name is " . <span> . "<br>"<span>?></span></span></span></span></span></span></span></span></span></span></span></span></span>

　　这次的运行结果是：my name is what，说明

<span php><span> = "why"<span><span function><span changename><span global> <span><span><span> = "what"<span><span function><span changename2><span> = "where"<span changename changename2><span echo> "my name is " . <span> . "<br>"<span>?></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>

　

 

<span php><span> = "why"<span><span function><span changename><span>['name'] = "what"<span changename><span echo> "my name is " . <span> . "<br>"<span>?></span></span></span></span></span></span></span></span></span></span>

 

　　

<span php><span> = 1<span><span> = 2<span><span function><span test1><span>['var2'] = &<span>['var1'<span test1><span echo> <span> . "<br>"<span><span> = 1<span><span> = 2<span><span function><span test2><span global> <span>,<span><span><span> = &<span><span test2><span echo> <span> . "<br>"<span>?></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>

　　; 就可以访问它们。与所有其他超全局变量不同，$GLOBALS在PHP中总是可用的。另一个例子：

<span php><span> = 1<span><span function><span test1><span unset>(<span>['var1'<span test1><span echo> <span> . "<br>"<span><span> = 1<span><span function><span test2><span global> <span><span><span unset>(<span><span test2><span echo> <span><span>?></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>

　　

http://www.bkjia.com/PHPjc/749824.htmlwww.bkjia.comtruehttp://www.bkjia.com/PHPjc/749824.htmlTechArticle? = "why" = "what" changeName(); "my name is " . . "br/" ? 执行代码的结果是：my name is why，而不是执行changeName()后显示what。分析原因，这是因为 函数体...

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