<?php?>、echo
php相关代码都要写在php和后面的？之间
echo：就是向网页中输出字符串
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>PHP页面</title>
</head>
<body>
<div>PHP to hello world</div>
<?php
// 所有的php代码都要写在这里
// echo 就是向网页输出字符串
/*
段注释
*/
echo "<div>这里是一个最简单的php动态网站</div>";
?>
</body>
</html>
变量及区分单双引号
php变量由$符号开始，后跟变量名。
变量名由字母数字下划线组成，不能以数字开头，区分大小写
字符串由点连接
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>PHP页面</title>
</head>
<body>
<div>PHP to hello world</div>
<?php
$num = 123;
// php中单引号和双引号不同
echo "<div>变量值为:$num</div>";//变量输出是123
echo '<div>变量值为:$num</div>';//变量输出是$num
// 字符串的拼接，php由点连接，JavaScript由+连接
echo "<div>变量值为:".$num."</div>";
?>
</body>
</html>
创建数组、echo、print_r()、var_dump()区别
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>PHP页面</title>
</head>
<body>
<div>测试页面</div>
<?php
// 创建数组
$arr=array(1,2,3,4);
$arr1 =array("name","yes");
$arr2 =array("key"=>"value","word"=>"yes");
// echo $arr;-//输出报错
echo $arr[0]; //1
echo "\n"; // 不识别\n换行
echo $arr[1];
echo "<br>"; //换行
echo $arr[2];
echo "<br>";
print_r($arr1);//Array ( [0] => name [1] => yes )
echo "<br>";
var_dump($arr2);//比print_r()打印详细点
?>
</body>
</html>
二维数组
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>PHP页面</title>
</head>
<body>
<div>测试页面</div>
<?php
// 创建二维数组
$arr =array();
$arr[0] =array(1,2,3);
$arr[1]=array(4,5,6);
$arr[2]=array(7,8,9);
print_r($arr);
// Array ( [0] => Array ( [0] => 1 [1] => 2 [2] => 3 )
// [1] => Array ( [0] => 4 [1] => 5 [2] => 6 )
// [2] => Array ( [0] => 7 [1] => 8 [2] => 9 )
// )
$arr1 =array(10);
$arr1["house1"] =array("area"=>234,"room"=>4);
$arr1["house2"] =array("area"=>334,"room"=>6);
echo "<br>";
print_r($arr1);
// Array ( [0] => 10 [house1] => Array ( [area] => 234 [room] => 4 )
// [house2] => Array ( [area] => 334 [room] => 6 ) )
?>
</body>
</html>
常见数据类型及调用函数
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>PHP页面</title>
</head>
<body>
<div>测试页面</div>
<?php
$arr =array(1,2,3,4);
//gettype()函数
echo "<br>";
echo gettype($arr);//array
$num =23;
echo "<br>";
echo gettype($num);//integer
$num =23.3;
echo "<br>";
echo gettype($num);//double
$bool =true;
echo "<br>";
echo gettype($bool);//boolean
echo "<br>";
//for循环,count计算数组长度
for($i=0;$i<count($arr);$i++){
print_r($arr[$i]);
}
echo "<br>";
//foreach遍历
foreach ($arr as $key => $value) {
echo $key."--->".$value."<br>";
}
?>
</body>
</html>
自定义函数
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>PHP页面</title>
</head>
<body>
<div>测试页面</div>
<?php
// 自定义函数,函数名不区分大小写，与js的不同
$res=FunName(13,3);//先调用不受影响，与js类似
echo $res;
echo "<br>";
function funName($num,$num1){
return $num+$num1;
}
$res=funName(23,3);
echo $res;
echo "<br>";
//系统函数，将数组变为json数据
// $arr =array(1,2,3);//[1,2,3]
$arr =array("key"=>"23","sum"=>"ouver");//{"key":"23","sum":"ouver"}
$json =json_encode($arr);
echo $json;
?>
</body>
</html>
http协议常用请求方式及在php中的用法
- get 用来从服务器获取数据（获取的参数一般用来查询）
- post 添加数据
- put 修改数据
- delete 删除数据
<?php
/*
获取从网页获取的数据，?连接
http://jditems.com/php/page.php?flag=3
*/
$var=$_GET['flag'];
echo "<p>$var</p>";
?>
post小用例
目录：
page.php
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>PHP页面</title>
</head>
<body>
<div>测试页面</div>
<div>
<!-- form默认method为get -->
<form action="page2.php" method="post">
用户名：<input type="text" name="username"><br>
密 码：<input type="password" name="pw"><br>
<input type="submit" value="提交">
</form>
</div>
</body>
</html>
paga2.php
网页和服务器简单交互案例
根据学号查询成绩
page.php
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>PHP页面</title>
</head>
<body>
<div>测试页面</div>
<div>
<!-- form默认method为get -->
<form action="page2.php" method="post">
学 号：<input type="text" name="id"><br>
<input type="submit" value="提交">
</form>
</div>
</body>
</html>
page2.php
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>后台</title>
</head>
<body>
<?php
// 相当于后台
$arr =array();
$arr['100'] =array("name"=>"小红","chinese"=>"120","math"=>"120","english"=>"134");
$arr['102'] =array("name"=>"小名","chinese"=>"124","math"=>"70","english"=>"124");
$arr['112'] =array("name"=>"小东","chinese"=>"110","math"=>"130","english"=>"90");
$id =$_POST['id'];
$score = $arr[$id];
echo "<ul><li>姓名：$score[name]</li><li>语文：$score[chinese]</li><li>数学：$score[math]</li><li>英语：$score[english]</li></ul>";
?>
</body>
</html>