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：

        $myAge = 25;
        switch($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：

        $myAge = 25;
        switch($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]);

 
        $languages = array("HTML/CSS",
        "JavaScript", "PHP", "Python", "Ruby");

        unset($languages[3]);

        foreach($languages as $lang) {
          print "
$lang
";
        }
        />

for循环

 
        // 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。

 
          $langs = array("JavaScript",
          "HTML/CSS", "PHP",
          "Python", "Ruby");

          foreach ($langs as $lang) {
              echo "
$lang
";
          }

          unset($lang);
        ?>

while 循环

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

endwhile的使用

     $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

$flipCount = 0;
    do {
        $flip = rand(0,1);
        $flipCount ++;
        if ($flip){
            echo "
H
";
        }
        else {
            echo "
T
";
        }
    } while ($flip);
    $verb = "were";
    $last = "flips";
    if ($flipCount == 1) {
        $verb = "was";
        $last = "flip";
    }
    echo "
There {$verb} {$flipCount} {$last}!
";
    ?>

函数

字符串内建函数

• strlen 返回字符串的长度

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

• substr 截取字符串函数，返回截取到的子字符串

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

• strtoupper 将字符串转为大写

 

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

• strtolower 将字符串转为小写

  
    $name = "CHENGFANGPENG";
    print strtolower($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。

 

    $name = "chengfangpeng";
    print strpos($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。

 
      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
 $name = "chengfangpeng";
    $rIndex = rand(0, strlen($name));
    print substr($name, $rIndex, 1);
    ?>