PHP快速入门（1）

PHP快速入门（1）——基本语法，控制结构和简单的面向对象

本文提供的所有程序已在PHP5下经过测试 。转载请注明出处。

 

# 快速开始 

<?php 

    echo "<p>Hello World </p>"; 

?>

# 注释

<?php 

    // 介是单行注释

    /* 介是多行注释... */ 

    echo "<p>This is something about php </p>";

?>

# 链接字符串 

<?php

    $str1 = "You will see: ";

    $str2 = "How to concat strings.";

    echo "<p>".$str1.$str2."</p>";

?>

# 条件判断 

<?php

    $flag = true;

    if($flag)

    {

        echo "<p>Under the condition...</p>";

    }

    else

    {

        echo "<p>Under other conditions...</p>";

    }



    $val = 100;

    if($val == 0) 

    {

        echo "<p>It is zero.</p>";

    }

    elseif($val < 0)

    {

        echo "<p>It is a negative.</p>";

    }

    else

    {

        echo "<p>It is a positive.</p>";

    }

?>

# 分支结构 

<?php

    $case = 10;

    $result = "";

    switch($case)

    {

        case 1:

            $result = "In case one.";

            break;

        case 2:

            $result = "In case two.";

            break;

        case 3:

            $result = "In case three.";

            break;

        default:

            $result = "In other case.";

            break;

    }

    echo "<p>".$result."</p>";

?>

# 三元运算 

<?php

    $val = 1;

    $exp = ($val == 0) ? "<p>The value is zero</p>" : "<p>The value is not zero</p>";

    echo $exp;

?>

# 数组array 

<?php

    echo "<ul>";

    $arr1 = array("John", "Jane", "Julie");

    echo "<li>People in array #1: $arr1[0], $arr1[1], $arr1[2]</li>";



    $arr2 = array(0 => "Jodan", 1 => "Jack", 2 => "James");

    echo "<li>People in array #2: $arr2[0], $arr2[1], $arr2[2]</li>";



    $arr3 = array(1 => "Tom", "Sam", "Kim");

    echo "<li>People in array #3: $arr3[1], $arr3[2], $arr3[3]</li>";

    

    $arr4[3] = "Avril";

    $arr4[2] = "Taylor";

    $arr4[1] = "Miley";

    echo "<li>People in array #4: $arr4[1], $arr4[2], $arr4[3]</li>";

    echo "</ul>";

?>

# for循环和foreach

<?php

    $fib[0] = 1;

    $fib[1] = 1;

    for($i = 2; $i < 10; $i++)

    {

        $fib[$i] = $fib[$i-1] + $fib[$i-2];        

    }



    echo "<p>The Fibonacci: ";

    foreach($fib as $index => $value)

    {

        echo (string)$value." ";

    }

    echo "</p>";

?>

# while循环 

<?php

    $n = 6;

    $c = 1;

    $r = 1;

    while($c <= $n)

    {

        $r *= $c;

        $c += 1;

    }

    echo "<p>$n != $r </p>";

?>

# 函数和递归 

<?php

    function factorial($val)

    {

        if($val == 0) return 1;

        return $val * factorial($val - 1);

    }

    $n = 7;

    echo "<p>$n! = ".(string)factorial($n)."</p>";

?>

# 简单的面向对象 

<?php

    class User

    {

        // fields

        private $name;

        private $email;

        private $status;



        // constructor

        function User($name, $email)

        {

            $this->name = $name;

            $this->email = $email;

            $this->status = "";

        }

        

        // getters

        function getName() { return $this->name; }

        function getEmail() { return $this->email; }

        function getStatus() { return $this->status; }

        

        // setters

        function setStatus($value) { $this->status = $value; }



        // methods

        function SignOut()

        {

            echo "User $this->name signed out.";

        }

    }



    $u = new User("John", "johnsmith@gmail.com");

    $u->setStatus("online");

    echo "<p>";

    echo "Name: ".$u->getName()."<br />";

    echo "Email: ".$u->getEmail()."<br />";

    echo "Status: ".$u->getStatus()."<br />";

    echo "</p>";

    echo "<p>".$u->SignOut()."</p>";

?>

# 更简单的Getter和Setter

<?php

    class Rectangle

    {

        // fields

        private $offsetX;

        private $offsetY;

        private $width;

        private $height;



        // constructor & destructor

        function __construct($x, $y)

        {

            $this->offsetX = $x;

            $this->offsetY = $y;

        }



        function __destruct()

        {

            unset($this->offsetX);

            unset($this->offsetY);

            unset($this->width);

            unset($this->height);

        }

        

        // getters

        function __get($property)

        {

            if(isset($this->$property)) { return($this->$property); }

            else return(NULL);

        }

        

        // setters

        function __set($property, $value) { $this->$property = $value; }

        



        // methods

        function GetArea()

        {

            return $this->width * $this->height;

        }

    }



    $rect = new Rectangle(10, 20);

    $rect->width = 48;

    $rect->height = 72;

    echo "<p>";

    echo "Offset X: ".$rect->offsetX."<br />";

    echo "Offset Y: ".$rect->offsetY."<br />";

    echo "Width: ".$rect->width."<br />";

    echo "Height: ".$rect->height."<br />";

    echo "Area: ".$rect->GetArea();

    echo "</p>";    

?>