PHP基础

<?php

//注释语法
/* 多行注释 */

//输出语法
//echo "hello";
//echo "world","dhakj"; //可以输出多个字符串

//print "aaa"; //只能输出一个字符串

//print_r(); //打印数组
//var_dump(); //输出变量及类型

//变量定义
//数据类型，弱类型语言
//$a = "hello";
//$hello = "world";

//echo $$a; //可变变量

//类型转换
//$a = 6;
//$b = (string)$a; //类型转换
//settype($a,"string"); //另外方式
//var_dump($a);

//运算符与表达式
//$a = 6;
//$b = 7;

//$c = $a == $b;
//var_dump($c);

//$a = "hello";
//$b = "world";
//$c = $a.$b; //拼接字符串用的是点（.）
//echo $c;

//$a = 8;
//@$c = $a/$b; //错误抑制符
//echo $c;

//php里面的错误信息
//Notice:提醒
//warning:警告
//error:错误

//三元运算符
//$a = 4;
//$b = 5;
//echo $a==$b?"相等":"不相等";

语句
顺序
$a = 5;
$b = 6;
分支
/*if($a==$b)
{
echo "相等";
}
else
{
echo "不相等";
}

switch($a)
{
case 4:
echo "4444";
break;
case 5:
echo "55555";
break;
case 6:
echo "66667";
break;
default:
echo "000000";
}

循环
for($a=0;$a<10;$a++)
{
echo $a;
}

while(true)
{
echo "aaa";
}

do
{

}
while()
?>