1)break

作用:跳过当前一个循环体

eg1:

<pre name="code" class="php"><pre name="code" class="php" style="font-size: 12px;"><?php
<span style="color:#330033;">for</span>($a=1;$a<10;$a++){
	echo '======<br/>';
<span style="background-color: rgb(0, 0, 153);"><span style="color:#ffff00;">	for($b=$a;$b<10;$b++){
		if($b==5){
			break;
			echo 'hi';
		}else{
		echo $a.'*'.$b.'<br/>';
		}
	}</span></span>

//如果此行有代码,时break生效时,执行权从黄色的for循环体直接跳到此行.
}
?>

执行结果:

<span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">1*1</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">1*2</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">1*3</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">1*4</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">2*2</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">2*3</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">2*4</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">3*3</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">3*4</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">4*4</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">6*6</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">6*7</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">6*8</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">6*9</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">7*7</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">7*8</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">7*9</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">8*8</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">8*9</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">9*9</span>

2)continue

跳过当前一个循环体中的一次循环

eg2:

<?php
for($a=1;$a<10;$a++){
	echo '======<br/>';
	<span style="color:#ff0000;">for</span>($b=$a;$b<10;$b++){
		if($b==5){
<span style="color:#ffff00;background-color: rgb(0, 0, 153);">			continue;
			echo 'hi';</span>
		}else{
		echo $a.'*'.$b.'<br/>';
		}
	}
}
?>

执行结果:

<span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">1*1</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">1*2</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">1*3</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">1*4</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">1*6</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">1*7</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">1*8</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">1*9</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">2*2</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">2*3</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">2*4</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">2*6</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">2*7</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">2*8</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">2*9</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">3*3</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">3*4</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">3*6</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">3*7</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">3*8</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">3*9</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">4*4</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">4*6</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">4*7</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">4*8</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">4*9</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">5*6</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">5*7</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">5*8</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">5*9</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">6*6</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">6*7</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">6*8</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">6*9</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">7*7</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">7*8</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">7*9</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">8*8</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">8*9</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">======</span><br style="font-family: Times;" /><span style="font-family: Times;font-size:14px;">9*9</span>

3)reutrn

中断函数,并返回一个值(也可能是NULL)

break,continue,return的区别