PHP process control_PHP tutorial-PHP Tutorial-php.cn

PHP process control_PHP tutorial

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Release： 2016-07-13 17:14:02

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if statement, switch statement, while loop, do...while loop, for loop, foreach loop, break interrupt loop, continue instruction. These are demonstrated below using the day of the week function.

Three process control structures of the program

1. Sequential structure
2. Select structure
3. Loop structure

The results are as follows

The code is as follows

Copy code

$d=date("D");

代码如下	复制代码
$d=date("D"); if ($d=="Tue") echo "今天是星期二"; else echo "今天不是星期二"; ?>

if ($d=="Tue")

echo "Today is Tuesday";

else

echo "Today is not Tuesday";

代码如下	复制代码
$srttime=date("w",time()); $array=array('天','一','二','三','四','五','六'); $todaytime=date("Y年m月d日星期{$array[$srttime]}",time()); echo $todaytime; ?>

You can determine the day of the week through the array. The execution result should be as follows

The code is as follows	Copy code
$srttime=date("w",time()); $array=array('天','一','二','三','四','五','六'); $todaytime=date("Y year m month d day week {$array[$srttime]}",time()); echo $todaytime; ?>

1. if (条件一) {

?⑹?/p>

}

IF - 1

    $a = 100 ;
    if ( $a == 100 ) {
    echo "A is 100. ";
    }
?>

或

if (条件一) {

?⑹鲆?/p>

} else {

?⑹龆?/p>

}

IF … ELSE - 1

            $a = 120 ;
        if ($a < 100 ) {
            echo " A was small than 100. ";
       }
       else {
            echo " A was big than 100. ";
       }
?>

IF … ELSE - 2

            $file = "files.txt" ;
        if ( file_exists($file) ) {        //?z查?n案是否存在
            echo " ?是?n案 files.txt的?热?
";
            readfile ($file) ;                  //?出?n案?热?br />         }
        else {
            echo " ?o此?n案
";
        }
    ?>

或

if (条件一) {

?⑹鲆?/p>

} elseif {

?⑹龆?/p>

} elseif {

?⑹鋈?/p>

}

...........

else {

?⑹?

}

    IF … ELSEIF … ELSE - 1


                    $a = 100 ;
            $b = 200 ;
            if ($a > $b) {
                echo "a is bigger than b";

} elseif ($a == $b) {
echo "a is equal to b";

            } else {
                print "a is smaller than b";
            }
        ?>

2. while (条件一) { //条件?檎? ??

?⑹鲆?/p>

}

WHILE

            $a = 1 ;
        while ( $a < 10 ) {
            echo "$a
";
            $a++;
        }
    ?>

3. do {

?⑹?/p>

} while (条件); //条件?檎? ??

Do .. WHILE - 1

            $a = 1 ;
        do {
            echo "$a
";
            $a++;
        } while ( $a < 10 )
    ?>

4. for (初始条件; 判?嗵跫? 条件改??⑹? {

?⑹?/p>

}

For - 1

            for ( $a = 1 ; $a < 10 ; $a++ )
        {
            echo "$a
";
        }
    ?>

5. break //中?嗾?诘霓?圈

BREAK

            $abc[0] = '0' ;
        $abc[1] = '1' ;
        $abc[2] = '2' ;
        $a = 0 ;
        while ( $a < 4 )
        {
            if ( $abc[$a] == '2' ) {    //若?檎? 跳?while()?圈
            break;
        }
            echo "$a";
            $a++;
        }
    ?>

6. continue //中?嗾?诘霓?圈, 跳到?圈????下一次

CONTINUE

for ($i=10; $i>1; $i--) {
                       continue;
            }
echo "$i
";
            }
?>

7. switch (condition) {

case 'case value 1':
             break;
case 'case value 2:
                                                                    break;
                                                  …                                                                  but                                           default:
                      ?⑹?
                 break;

}

SWITCH

switch ($i) {
case 0:
                     echo "i equals 0";
case 1:
                    echo "i equals 1";
case 2:
                       echo "i equals 2";
          }
?>

Switch - SWITCH

            switch ( $a ) {
            case '1':
                echo "one";
                break;
            case '2':
                echo "two";
                break;
            case '3':
                echo "three";
                break;
            case '4':
                echo "four";
                break;
            case '5':
                echo "five";
                break;
            default:
                echo "ZERO";
                break;
        }
?>

注意事项

PHP 语法中在每条指令结束时都要加上分号 ;，但是在部分结尾符号 } 后面不用加上分号结束。
在流程的部分分隔符号上，都是使用 { 当作部分的开头，用 } 当作结尾，和 C 语言相同。不过 C 可以定义 begin 当开头、end 当结尾 (像 Pascal)，而 PHP 中不能做这种特殊的定义。