Php笔记-基础语法

变量

php 的变量必须用$开头

$myAge

switch语法

switch有两种语法：

• 正常的语法：

<?php        $myAge = 25;        switch($myAge){            case 20:                print "your are age is 20";                break;            case 24:                print "your are age is 24";                break;            case 25:                print "your are age is 25";                break;            default:                print "your are age is not match";                break;        }

• sugar语法：

<?php        $myAge = 25;        switch($myAge):            case 20:                print "your are age is 20";                break;            case 24:                print "your are age is 24";                break;            case 25:                print "your are age is 25";                break;            default:                print "your are age is not match";                break;        endswitch;    ?>

数组

 $array = array("cheng", "fang", "peng");

获取数组的值有两种方法

• 通过[]

    $array[2]；

• 通过{}

 $array{2}

数组中删除元素

unset(array[2]);

 <?php        $languages = array("HTML/CSS",        "JavaScript", "PHP", "Python", "Ruby");        unset($languages[3]);        foreach($languages as $lang) {          print "<p>$lang</p>";        }        />

for循环

 <?php        // 输出前五个偶数        for ($i = 2; $i < 11; $i = $i + 2) {          echo $i;        }      ?>

foreach循环

foreach循环是迭代对象里的每一个元素。

 <?php          $langs = array("JavaScript",          "HTML/CSS", "PHP",          "Python", "Ruby");          foreach ($langs as $lang) {              echo "<li>$lang</li>";          }          unset($lang);        ?>

while 循环

<?php    $headCount = 0;    $flipCount = 0;    while ($headCount < 3) {        $flip = rand(0,1);        $flipCount ++;        if ($flip){            $headCount ++;            echo "<div class=\"coin\">H</div>";        }        else {            $headCount = 0;            echo "<div class=\"coin\">T</div>";        }    }    echo "<p>It took {$flipCount} flips!</p>";    ?>

endwhile的使用

<?php     $isLoop = true;     $index = 0;    while($isLoop):        if($index > 10){            $isLoop = false;            }            echo $index;            $index++;    endwhile;        ?>

do-while的使用

先执行do中的代码，然后再执行while循环

<?php    $flipCount = 0;    do {        $flip = rand(0,1);        $flipCount ++;        if ($flip){            echo "<div class=\"coin\">H</div>";        }        else {            echo "<div class=\"coin\">T</div>";        }    } while ($flip);    $verb = "were";    $last = "flips";    if ($flipCount == 1) {        $verb = "was";        $last = "flip";    }    echo "<p>There {$verb} {$flipCount} {$last}!</p>";    ?>

函数

字符串内建函数

• strlen 返回字符串的长度

 <?php        $name = "chengfangpeng";        print strlen($name);    ?>

• substr 截取字符串函数，返回截取到的子字符串

  <?php       $name = "chengfangpeng";        print substr($name, 5, 10);    ?>

• strtoupper 将字符串转为大写

 <?php    $name = "chengfangpeng";    print strtoupper($name);    ?>

• strtolower 将字符串转为小写

  <?php    $name = "CHENGFANGPENG";    print strtolower($name);    ?>

• strpos 找出字符串中某个子字符串的位置，如果没有所给的字符串，返回false，否则返回子字符串在原字符串中的位置。

 <?php    $name = "chengfangpeng";    print strpos($name, "fang");    if(strpos($name, "Hello") === false){        print "no match string";    }    ?>

数学内建函数

• round 将一个float类型的数，四舍五入为整形，如果再传入保留位数参数可以转化成保留小数位的float类型。

 <?php      print round(M_PI); //3      print round(M_PI, 3);//3.142    ?>

//使用rand，strlen，substr函数随机打印你姓名中的一个字母 <?php    $name = "chengfangpeng";    $rIndex = rand(0, strlen($name));    print substr($name, $rIndex, 1);    ?>