PHP在循环内外实例化类在占用内存上有很大的区别

关于php类的实例化和内存的关系，可以这么说:只要有一个new 关键字就是创建一个对象，创建一个对象就是在内存中分配了一个空间 ，那么OK，看代码。

view sourceprint?

01.

<?php

02.

class

ABC{

03.

public

$numBox

=

array

();

04.

public

function

ddd(){

05.

for

(

$i

=1;

$i

<=600;

$i

++){

06.

$this

->numBox[]
=mt_rand(1,1000000);

07.

}

08.

echo

'Now
memory_get_usage: '

.memory_get_usage().

'<br
/>'

;

09.

}

10.

11.

}

12.

$instance

=

new

ABC();

13.

for

(

$i

=0;

$i

<
50 ;

$i

++){

14.

$instance

->ddd();

15.

}

16.

?>

这是上面的代码在我的机器上面运行的结果：

Now memory_get_usage: 424312

Now memory_get_usage: 476408

Now memory_get_usage: 524408

Now memory_get_usage: 580608

Now memory_get_usage: 628608

Now memory_get_usage: 676608

Now memory_get_usage: 740992

Now memory_get_usage: 789000

Now memory_get_usage: 837000

Now memory_get_usage: 885000

Now memory_get_usage: 933000

Now memory_get_usage: 981000

Now memory_get_usage: 1029000

Now memory_get_usage: 1109768

Now memory_get_usage: 1157768

Now memory_get_usage: 1205768

Now memory_get_usage: 1253768

Now memory_get_usage: 1301768

Now memory_get_usage: 1349768

Now memory_get_usage: 1397768

Now memory_get_usage: 1445768

Now memory_get_usage: 1493768

view sourceprint?

01.

<?php

02.

class

ABC{

03.

public

$numBox

=

array

();

04.

public

function

ddd(){

05.

for

(

$i

=1;

$i

<=600;

$i

++){

06.

$this

->numBox[]
=mt_rand(1,1000000);

07.

}

08.

echo

'Now
memory_get_usage: '

.memory_get_usage().

'<br
/>'

;

09.

}

10.

11.

}

12.

13.

for

(

$i

=0;

$i

<
50 ;

$i

++){

14.

$instance

=

new

ABC();

15.

$instance

->ddd();

16.

}

17.

?>

这个是上面的代码运行的结果：

Now memory_get_usage: 424552

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

Now memory_get_usage: 424536

OK，其实，只要有一个new 关键字就是创建一个对象，创建一个对象就是在内存中分配了一个空间，每次重新分配内存一定是要占用更多的内存的，所以，我们要对的类的实例化要注意，这样也就是为什么要使用单实例设计模式，因为这样可以节约内存。