第五章_PHP流程控制_PHP教程
- WBOY原创
- 2016-07-13 17:17:25792浏览
1.顺序结构
2.分支结构
2.1 if...else
<span 1</span> <?<span php
</span><span 2</span> <span $today</span>=<span date</span>("w"); <span //</span><span 获取今天星期几</span>
<span 3</span> <span if</span>(<span $today</span>==0<span ){
</span><span 4</span> <span echo</span> 'Sunday!'<span ;
</span><span 5</span> }<span else</span><span {
</span><span 6</span> <span echo</span> 'Sorry!'<span ;
</span><span 7</span> <span }
</span><span 8</span> ?>
2.2 if...elseif
2.3 switch
3.循环结构
3.1 while
<span 1</span> <?<span php
</span><span 2</span> <span $num</span>=1<span ;
</span><span 3</span> <span while</span>(<span $num</span><=100<span ){
</span><span 4</span> <span echo</span> <span $num</span>.' '<span ;
</span><span 5</span> <span $num</span>++<span ;
</span><span 6</span> <span }
</span><span 7</span> ?>
3.2 do...while
与C/C++类似
3.3 for
<span 1</span> <?<span php
</span><span 2</span> <span $week</span>=<span array</span>('Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday'<span );
</span><span 3</span> <span $size</span>=<span count</span>(<span $week</span><span );
</span><span 4</span> <span echo</span> '数组大小'.<span $size</span>.'<p>'<span ;
</span><span 5</span> <span for</span>(<span $i</span>=0;<span $i</span><<span $size</span>;<span $i</span>++<span ){
</span><span 6</span> <span echo</span> <span $week</span>[<span $i</span>].' '<span ;
</span><span 7</span> <span }
</span><span 8</span> ?>
3.4 foreach
foreach语句专门用来遍历数组的，有两种语法格式：
①foreach(数组名 as 元素名){
语句块;
}
②foreach(数组名 as 键名 => 元素名){
语句块;
}
前者举例如下：
<span 1</span> <?<span php
</span><span 2</span> <span $week</span>=<span array</span>('Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday'<span );
</span><span 3</span> <span $size</span>=<span count</span>(<span $week</span><span );
</span><span 4</span> <span echo</span> '数组大小'.<span $size</span>.'<p>'<span ;
</span><span 5</span> <span foreach</span>(<span $week</span> <span as</span> <span $value</span><span ){
</span><span 6</span> <span echo</span> <span $value</span>.' '<span ;
</span><span 7</span> <span }
</span><span 8</span> ?>
后者举例如下：
<span 1</span> <?<span php
</span><span 2</span> <span $week</span>=<span array</span>('星期日'=>'Sunday','星期一'=>'Monday','星期二'=>'Tuesday','星期三'=>'Wednesday','星期四'=>'Thursday','星期五'=>'Friday','星期六'=>'Saturday'<span );
</span><span 3</span> <span $size</span>=<span count</span>(<span $week</span><span );
</span><span 4</span> <span echo</span> '数组大小'.<span $size</span>.'<p>'<span ;
</span><span 5</span> <span foreach</span>(<span $week</span> <span as</span> <span $key</span>=><span $value</span><span ){
</span><span 6</span> <span echo</span> <span $key</span>.':'.<span $value</span>.' '<span ;
</span><span 7</span> <span }
</span><span 8</span> ?>
4.break 与 continue
break后面可以接一个数字，表示跳出第几重循环，continue后面也可以接一个数字，表示跳出第几重循环后面尚未执行的语句。
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