php变量前面加&符号是什么意思就不用多说了,大家都在用,就是两个变量同时指向一个地址而已,那么,php函数前面加&符号的意义又是什么呢?下面先上两个演示代码,然后再做解释。

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<span style="color: #000000;font-weight: bold">function</span> <span style="color: #339933">&</span>chhua<span style="color: #009900">(</span><span style="color: #009900">)</span>   
<span style="color: #009900">{</span>   
static <span style="color: #000088">$b</span><span style="color: #339933">=</span><span style="color: #0000ff">"www.chhua.com"</span><span style="color: #339933">;</span><span style="color: #666666;font-style: italic">//申明一个静态变量   </span>
<span style="color: #000088">$b</span><span style="color: #339933">=</span><span style="color: #000088">$b</span><span style="color: #339933">.</span><span style="color: #0000ff">"WEB开发"</span><span style="color: #339933">;</span>   
<span style="color: #b1b100">echo</span> <span style="color: #000088">$b</span><span style="color: #339933">;</span>   
<span style="color: #b1b100">return</span> <span style="color: #000088">$b</span><span style="color: #339933">;</span>   
<span style="color: #009900">}</span>   
 
<span style="color: #000088">$a</span><span style="color: #339933">=</span>chhua<span style="color: #009900">(</span><span style="color: #009900">)</span><span style="color: #339933">;</span><span style="color: #666666;font-style: italic">//这条语句会输出 $b的值 为“www.chhua.comWEB开发”   </span>
<span style="color: #000088">$a</span><span style="color: #339933">=</span><span style="color: #0000ff">"PHP"</span><span style="color: #339933">;</span>   
<span style="color: #b1b100">echo</span> <span style="color: #0000ff">"<Br>"</span><span style="color: #339933">;</span>
<span style="color: #000088">$a</span><span style="color: #339933">=</span>chhua<span style="color: #009900">(</span><span style="color: #009900">)</span><span style="color: #339933">;</span><span style="color: #666666;font-style: italic">//这条语 句会输出 $b的值 为“www.chhua.comWEB开发WEB开发”     </span>
<span style="color: #b1b100">echo</span> <span style="color: #0000ff">"<Br>"</span><span style="color: #339933">;</span>
<span style="color: #000088">$a</span><span style="color: #339933">=&</span>chhua<span style="color: #009900">(</span><span style="color: #009900">)</span><span style="color: #339933">;</span><span style="color: #666666;font-style: italic">//这条语句会输出 $b的值 为“www.chhua.comWEB开发WEB开发WEB开发”   </span>
<span style="color: #b1b100">echo</span> <span style="color: #0000ff">"<Br>"</span><span style="color: #339933">;</span>
<span style="color: #000088">$a</span><span style="color: #339933">=</span><span style="color: #0000ff">"JS"</span><span style="color: #339933">;</span>   
<span style="color: #000088">$a</span><span style="color: #339933">=</span>chhua<span style="color: #009900">(</span><span style="color: #009900">)</span><span style="color: #339933">;</span> <span style="color: #666666;font-style: italic">//这条语句会输出 $b的值 为"JSWEB开发"</span>
 
 
<span style="color: #000000;font-weight: bold">function</span> <span style="color: #339933">&</span>test<span style="color: #009900">(</span><span style="color: #009900">)</span>
<span style="color: #009900">{</span>
	static <span style="color: #000088">$b</span><span style="color: #339933">=</span><span style="color: #cc66cc">0</span><span style="color: #339933">;</span><span style="color: #666666;font-style: italic">//申明一个静态变量</span>
	<span style="color: #000088">$b</span><span style="color: #339933">=</span><span style="color: #000088">$b</span><span style="color: #339933">+</span><span style="color: #cc66cc">1</span><span style="color: #339933">;</span>
	<span style="color: #b1b100">echo</span> <span style="color: #000088">$b</span><span style="color: #339933">;</span>
	<span style="color: #b1b100">return</span> <span style="color: #000088">$b</span><span style="color: #339933">;</span>
<span style="color: #009900">}</span>
 
<span style="color: #000088">$a</span><span style="color: #339933">=</span>test<span style="color: #009900">(</span><span style="color: #009900">)</span><span style="color: #339933">;</span><span style="color: #666666;font-style: italic">//这条语句会输出 $b的值 为1</span>
<span style="color: #000088">$a</span><span style="color: #339933">=</span><span style="color: #cc66cc">5</span><span style="color: #339933">;</span>
<span style="color: #000088">$a</span><span style="color: #339933">=</span>test<span style="color: #009900">(</span><span style="color: #009900">)</span><span style="color: #339933">;</span><span style="color: #666666;font-style: italic">//这 条语句会输出 $b的值 为2</span>
<span style="color: #000088">$a</span><span style="color: #339933">=&</span>test<span style="color: #009900">(</span><span style="color: #009900">)</span><span style="color: #339933">;</span><span style="color: #666666;font-style: italic">//这条语句会输出 $b的值 为3</span>
<span style="color: #000088">$a</span><span style="color: #339933">=</span><span style="color: #cc66cc">5</span><span style="color: #339933">;</span>
<span style="color: #000088">$a</span><span style="color: #339933">=</span>test<span style="color: #009900">(</span><span style="color: #009900">)</span><span style="color: #339933">;</span> <span style="color: #666666;font-style: italic">//这条语句会输出 $b的值 为6</span>

下面就来解释一下第二个函数吧。
通过这种方式$a=test();得到的其实不是函数的引用返回,这跟普通的函数 调用没有区别.

至于原因: 这是PHP的规定
php规定通过$a=&test(); 方式得到的才是函数的引用返回.

至于什么是引用返回呢(PHP手册上说:引用返回用在当想用函数找到引用应该被绑定在哪一个变量上面时。)

用上面的例子来解释就是
$a=test()方式调用函数,只是将函数的值赋给$a而已, 而$a做任何改 变 都不会影响到函数中的$b.
而通过$a=&test()方式调用函数呢, 他的作用是将return $b中的 $b变量的内存地址与$a变量的内存地址,
指向了同一个地方. 即产生了相当于这样的效果($a=&b) 所以改变$a的值,也同时改变了$b 的值 ,所以在执行了:
$a=&test(); $a=5; 以后,$b的值变为了5。