PHP基础（004）---流程控制语句浅析

代码一：（If ... else ...)

1 <?php
2 header("Content-type: text/html; charset=utf-8"); 
3 $boo = "028398";
4 if(is_numeric($boo)){
5     echo "这是个数字!";}   //output: 这是个数字!
6 else{
7     echo "不是个数字！";}
8     
9 ?>
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 代码二：(if...)

 1 <?php
 2 header("Content-type: text/html; charset=utf-8");
 3 $a=20;
 4 $b=100;
 5 if ($a > $b) {
 6     echo "a is bigger than b";
 7     echo "<br/>"; 
 8     $b = $a;
 9 }
10 echo $b;  //output : 100
11 
12 ?>
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 代码三：（if...elseif...else...)

 1 <?php
 2 
 3 if ($a == 5):
 4     echo "a equals 5";
 5     echo "...";
 6 elseif ($a == 6):
 7     echo "a equals 6";
 8     echo "!!!";
 9 else:
10     echo "a is neither 5 nor 6";   //output : a is neither 5 nor 6
11 endif;
12 ?>
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代码四：(do...while...)

1 <?php
2 $i = 0;
3 do {
4    echo $i;  //此循环将正好运行一次，因为经过第一次循环后，当检查表达式的真值时，其值为 FALSE（$i 不大于 0）而导致循环终止。
5 
6 } while ($i > 0);
7 ?>
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代码五：(foreach...)

 <?php
/* 示例1: value only */

$a = array(1, 2, 3, 17);

foreach ($a as $v) {
   echo "Current value of $a: $v. ";
  
}
 echo "<br/>";


/* 示例2: value (with its manual access notation printed for illustration) */

$a = array(1, 2, 3, 17);

$i = 0; /* for illustrative purposes only */

foreach ($a as $v) {
    echo "$a[$i] => $v ；";
    $i++;
}
echo "<br/>";


/* 示例3: key and value */

$a = array(
    "one" => 1,
    "two" => 2,
    "three" => 3,
    "seventeen" => 17
);

foreach ($a as $k => $v) {
    echo "$a[$k] => $v; ";
}
 echo "<br/>";

/* 示例4: 二维数组multi-dimensional arrays */
$a = array();
$a[0][0] = "a";
$a[0][1] = "b";
$a[1][0] = "y";
$a[1][1] = "z";

foreach ($a as $v1) {
    foreach ($v1 as $v2) {
        echo "$v2 ";
    }
}
 echo "<br/>";


/* 示例5: 动态数组dynamic arrays */

foreach (array(1, 2, 3, 4, 5) as $v) {
    echo "$v ";
}
?> 

output:
Current value of Array: 1. Current value of Array: 2. Current value of Array: 3. Current value of Array: 17. 
1 => 1 ；2 => 2 ；3 => 3 ；17 => 17 ；
1 => 1; 2 => 2; 3 => 3; 17 => 17; 
a b y z 
1 2 3 4 5
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 代码六：（switch...)

 1 <?php
 2 setlocale(LC_TIME,"chs");                                //设置本地环境
 3 $weekday = strftime("%A");                                //声明变量$weekday的值
 4 switch ($weekday){                                        //switch语句，判断$weekday的值
 5     case "星期一":                                        //如果变量的值为“星期一”
 6         echo "今天是$weekday ，新的一周开始了。";
 7         break;
 8     case "星期二":                                        //如果变量的值为“星期二”
 9         echo "今天是$weekday ，保持昨天的好状态，继续努力!";
10         break;
11     case "星期三":                                        //如果变量的值为“星期三”
12         echo "今天是$weekday ，真快啊，过去1/2周了。";
13         break;
14     case "星期四":                                        //如果变量的值为“星期四”
15         echo "今天是$weekday ，再上1天又放假了：）";
16         break;
17     case "星期五":                                        //如果变量的值为“星期五”
18         echo "今天是$weekday ，好好想想明天去那里玩。";
19         break;
20     default:                                            //默认值
21         echo "今天是$weekday , HOHO~~,可以放松了。";
22         break;
23 }
24 ?>
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 代码七：(while...for...嵌套循环)

<?php
while(true){
    for(;;){
        for($i=0;$i<=10;$i++){
            echo $i." ";
            if($i == 7){
                echo "<p>变量\$i等于9，跳出1重循环。<p>";
                break 1;
            }
        }
        for($j = 0; $j < 20; $j++){
            echo $j." ";
            if($j == 15){
                echo "<p>变量\$j等于15，跳出最外重循环。";
                break 3;
            }
        }
    }
    echo "这句话不会被执行。";
}
?>
output:
0 1 2 3 4 5 6 7
变量$i等于9，跳出1重循环。

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

变量$j等于15，跳出最外重循环。
View Code

 

posted on 2014-04-27 00:46  lbsf  阅读(135)  评论(0)    收藏  举报

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