PHP基础

<?php

//注释
/* 多行注释 */

输出语句
echo "hello","helloa";
print "world";

print_r(); //输出数组信息
var_dump();//变量和类型

变量定义

int float bool string
弱类型语言
/*$a = 10;
$b = "he{$a}llo";
$c = 'world';
$d = <<<AA
hello "aa" , "bb" ,'cc',
<input type="text" value="aa" />
AA;*/
1.双引号里面可以解析转义字符，单引号不行
2.双引号里面可以解析变量，单引号不行

//$e = $a.$c; //拼接字符串用的是.
//$f = 10.05;

//$f = (string)$f; //类型转换

//$f = "hello";

//$aa = "cc";
//$cc = "dd";
//echo $$aa; //可变变量
//$dd = &$aa; //&取地址
//$dd = "ee";
//echo $aa;

//运算符与表达式
$a = 10;
$b = 4;
//echo $a/$b;

//echo @$c; //错误抑制符，并不能抑制所有错误

//echo $a==$b?"ok":"no"; //三目运算符

//1.if...else...
//2.if...else if...
//3.if嵌套
/*$a = 2;
switch($a)
{
case 1:
echo "11111";
break;
case 2:
echo "222222";
break;
case 3:
echo "333333";
break;
default:
echo "444";
break;
}*/

//1.for
for($i=0;$i<10;$i++)
{
echo $i."<br>";
}
//2.while
//3.do...while

//echo $e;

//var_dump($f);

?>