php笔记

1. " ":解析变量。' ':当作文本处理

2.两种特别的类型：NULL和resource.    若类型

3.定义常量

define('AMOUNT',100);

使用常量

echo AMOUNT;

4.string操作符

$a = "Bob's ";

$b= "Auto Parts";

$result = $a.$b;

5.$b1 = 6+($a=5);结果为11

因为($a=5);这个表达式返回5.

6.比较操作符

===，值相等且类型相等。是否一致与是否相等(equal)

7.逻辑操作符

xor: $a x or $b,return true if either $a or $b is true, and false if they are both true or false.

8.if you have php set up with track_errors feature enabled in php.ini , the error message will be stored in the global variable $php_errormsg.