php基础知识

<?php
echo "Hello world";
echo "Last statement";
// 脚本至此结束，并无 PHP 结束标记

<?php
$expression = true;
include(relpath('./').'/index.html');

<?php

// 字符串连接
$num = 12.8;
$string = "this is world".$num;

// 双引号中使用变量
$world = "world";
$hello = "hello {$world}";

// 转义特殊字符
$class_name = "\\name";
echo $class_name;

// 数组
$array = array(
    "foo" => "bar",
    "bar" => "foo",
    100   => -100,
    -100  => 100,
);
var_dump($array['foo']);
unset ($array[100]);
$array["x"] = 42;


// 没有键名的索引数组
$array = array("foo", "bar", "hallo", "world");
var_dump($array);

// 遍历
foreach ($array as $key => $value) {
  var_dump($key, $value);
}

// 对象
class foo
{
    function do_foo()
    {
        echo "Doing foo.";
    }
}

$bar = new foo;
$bar->do_foo();

?>

<?php
$a = 1;
$b = 2;

function Sum()
{
    global $a, $b;
    $b = $a + $b;
}

Sum();
echo $b;

<?php
function fac($number)
{
  static $sum = 0;
  echo $sum . "\n";

  if ($number == 0) {
    $sum += $number;
    return 1;
  } else {
    $sum += $number;
    return $number * fac($number - 1);
  }
}
echo fac(4);

<?php

// 合法的常量名
define("FOO",     "something");
define("FOO2",    "something else");
define("FOO_BAR", "something more");

// 非法的常量名
define("2FOO",    "something");

// 下面的定义是合法的，但应该避免这样做：(自定义常量不要以__开头)
// 也许将来有一天PHP会定义一个__FOO__的魔术常量
// 这样就会与你的代码相冲突
define("__FOO__", "something");

<?php
class System {
  const OS_UNKNOWN = 1;
  const OS_WIN = 2;
  const OS_LINUX = 3;
  const OS_OSX = 4;

  /**
   * @return int
   */
  static public function getOS() {
    switch (true) {
      case stristr(PHP_OS, 'DAR'): return self::OS_OSX;
      case stristr(PHP_OS, 'WIN'): return self::OS_WIN;
      case stristr(PHP_OS, 'LINUX'): return self::OS_LINUX;
      default : return self::OS_UNKNOWN;
    }
  }
}

<?php
function foo($arg_1, $arg_2, /* ..., */ $arg_n)
{
    echo "Example function.\n";
    return $retval;
}

<?php
function add_some_extra(&$string)
{
    $string .= 'and something extra.';
}
$str = 'This is a string, ';
add_some_extra($str);
echo $str;
?>

<?php
function makecoffee($type = "cappuccino")
{
    return "Making a cup of $type.\n";
}
echo makecoffee();
echo makecoffee(null);
echo makecoffee("espresso");
?>

<?php
class C {}
class D extends C {}

// 并没有继承C
class E {}

function f(C $c) {
    echo get_class($c)."\n";
}

f(new C);
f(new D);
f(new E); // 这里会报错
?>

<?php
$method = "action";
function action()
{
  echo "foo";
}
// 可变函数
$method();

<?php
class simpleClass
{
  // public 代表可以在任何地方被访问
  public $var = 'a default value';

  // 类常量
  const pi = 3.1415926;

  // 任何地方可访问的一个方法
  public function displayVar()
  {
    //$this是一个到主对象的引用
    echo $this->var;
  }
}
// 利用new关键字生成一个对象
var simple = new simpleClass();

// 继承上一个类
class extendClass extends simplerClass
{
  function displayVar()
  {
    echo "Extending class\n";
    //调用父类中的方法
    parent::displayVar();
  }
}

<?php
class core
{
  public static function load()
  {
    // include
  }
}
spl_autoload_register('core::load');

// 调用了一个不存在的类 spl_autoload_register中指定的方法会被调用
// 类名 \core\lib\route 或作为参数传入core::load方法
new \core\lib\route();

<?php
class core
{
  public $action =  'index';
  function __construct($action)
  {
    public $action = $action;
  }
}

<?php
class route extends core
{
  function __construct()
  {
    // 调用父类的构造函数
    parent::__construct();
  }
}

<?php

// 在类外部使用
class MyClass {
  const CONST_VALUE = 'A constant value';
}

$classname = 'MyClass';
// 自 PHP 5.3.0 起
echo $classname::CONST_VALUE;

echo MyClass::CONST_VALUE;

// 在类内部使用
class OtherClass extends MyClass
{
  // static关键字是使用范围解析符的关键
  public static $my_static = 'static var';

  public static function doubleColon() {
    echo parent::CONST_VALUE . "\n";
    echo self::$my_static . "\n";
  }
}

$classname = 'OtherClass';
echo $classname::doubleColon(); // 自 PHP 5.3.0 起
OtherClass::doubleColon();

<?php
include(realpath('./').'/lib/core.php');
// 静态方法
\lib\core::load();

// 非静态方法
$o = new \lib\core();
$o->dump();

<?php
namespace lib;
class core
{
  public function dump()
  {
    //code
  }
  public static function load()
  {
    //code
  }
}

<?php

$db = array(
  'dsn' => 'mysql:host=localhost;dbname=test;port=3306;charset=utf8',
  'host' => 'localhost',
  'port' => '3306',
  'dbname' => 'yarn',
  'username' => 'root',
  'password' => 'root',
  'charset' => 'utf8',
);

//连接
$options = array(
  //默认是PDO::ERRMODE_SILENT, 0, (忽略错误模式)
  PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
  // 默认是PDO::FETCH_BOTH, 4
  PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
);

try{
  $pdo = new PDO($db['dsn'], $db['username'], $db['password'], $options);
}catch(PDOException $e){
  die('数据库连接失败:' . $e->getMessage());
}

//或者更通用的设置属性方式:
//设置异常处理方式
//$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
//设置默认关联索引遍历
//$pdo->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);

echo '<pre/>';

//1 查询

//1)使用query
//返回一个PDOStatement对象
$stmt = $pdo->query('select * from user limit 2');

//从结果集中获取下一行，用于while循环
//$row = $stmt->fetch();
//获取所有
$rows = $stmt->fetchAll();

$row_count = $stmt->rowCount();
//print_r($rows);

echo '<br>';

//2)使用prepare 推荐
$stmt = $pdo->prepare("select * from user where name = ? and age = ? ");
$stmt->bindValue(1,'test');
$stmt->bindValue(2,22);
//执行一条预处理语句 .成功时返回 TRUE, 失败时返回 FALSE
$stmt->execute();  
$rows = $stmt->fetchAll();
print_r($rows);



//2 新增、更新、删除
//1)普通操作
//$count  =  $pdo->exec("insert into user(name,gender,age)values('test',2,23)");
//echo $pdo->lastInsertId();

//$count  =  $pdo->exec("update user set name='test2' where id = 15");
//$count  =  $pdo->exec("delete from  user where id = 15");


//2)使用prepare 推荐!
/*
$stmt = $pdo->prepare("insert into user(name,gender,age)values(?,?,?)");
$stmt->bindValue(1, 'test');
$stmt->bindValue(2, 2);
$stmt->bindValue(3, 23);
$stmt->execute();
*/

//3)使用prepare 批量新增
$stmt = $pdo->prepare("insert into user(name,gender,age)values(?,?,?)");
$stmt->bindParam(1, $name);
$stmt->bindParam(2, $gender);
$stmt->bindParam(3, $age);

$data = array(
  array('t1', 1, 22),
  array('t2', 2, 23),
);

foreach ($data as $vo){
  list($name, $gender, $age) = $vo;
  $stmt->execute();
}

<?php
//开启事务处理
$pdo->beginTransaction();

try{
  //PDO预处理以及执行语句...
  $pdo->commit();
}catch(PDOException $e){
  $pdo->rollBack();

  //相关错误处理
  throw $e;
}

header("Location: http://example.com/myOtherPage.php");
header("Content-Type: text/json");

session_start();
$_SESSION;