如题,如果我这么创建代码
假如有一个Apple这个类。
<code>function abc() { $a = new Apple(); return a; } $a = abc(); $name = $a -> getname(); ...... </code>
经过上述这么调用后,是不是$a就不会自动被PHP垃圾处理器回收?
回复内容:
如题,如果我这么创建代码
假如有一个Apple这个类。
<code>function abc() { $a = new Apple(); return a; } $a = abc(); $name = $a -> getname(); ...... </code>
经过上述这么调用后,是不是$a就不会自动被PHP垃圾处理器回收?
struct _zval_struct {
<code>zvalue_value value; unsigned char type; unsigned char is_ref; short refcount;</code>
};
value:变量的值
type:变量的类型
is_ref:变量是否被引用
refcount:引用次数
重点在is_ref,如果为false,说明当前没有被按引用引用,且refcount为0时,则PHP垃圾回收机制会将其回收。
备注:函数中的$a在函数执行完毕后,立刻被回收。函数外的$a,必须被手动销毁,要么就是脚本执行完毕后,变量$a被销毁!
函数中的$a的话,函数执行完就被释放了。
函数外的$a如果你不unset的话,在脚本执行完之前都会存在。
函数中创建的Apple对象的话,因为你把它作为返回值,函数外的$a还保存着对Apple对象的引用,所以不会被回收。除非你把函数外的$a给unset了或者修改了它的值,使得没有对Apple对象的引用了,Apple对象才会被回收。
变量引用次数为零自然会被回收
确定后面不再使用全局变量$a,那执行unset($a)
释放掉就好了.
PHP的垃圾回收是基于引用计数实现的,具体看官方文档:
http://php.net/manual/zh/features.gc.php

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