1.常量的声明
在PHP中,定义常量使用define()函数来实现
2.魔术常量
| 返回文件中的当前行号 | |
| __FILE__ | 返回该文件的完整路径和文件名 |
| __DIR__ | 返回该文件所在的目录 |
| __FUNCTION__ | 返回该函数被定义时的名字 |
| __CLASS__ | 返回该类被定义时的名字 |
| __MTHOD__ | 返回该类的方法被定义时的名字 |
测试代码如下:
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<span> <?<span php><span> <span function><span sayhello><span> <span echo> '<p>the name of this function is:'.<span __function__><span><span> <span><span> <span> <span echo> '<p>这是第'.<span __line__>.'行。'<span><span> <span echo> '<p>本文件的绝对路径为:'.<span __file__><span><span> <span sayhello><span> ?></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>
3.引用赋值
用不同的变量名访问同一个变量内容,当其中一个变量的值改变时,另一个也跟着改变。
4.逻辑运算符
与 && 或 || 非 ! 异或 xor
<span> <?<span php><span> <span>=<span true><span><span> <span>=<span false><span><span> <span> <span var_dump>(<span> && <span>);<span echo> '<br>'<span><span> <span var_dump>(<span> || <span>);<span echo> '<br>'<span><span> <span var_dump>(<span> xor <span>);<span echo> '<br>'<span><span> <span var_dump>(!<span>);<span echo> '<br>'<span><span> ?></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>
5.比较运算符
①相等 == $a==$b 当$a的值等于$b的值,则返回真,否则返回假
②全等 === $a===$b 当$a的值等于$b的值,且$a与$b的类型也相等,则返回真,否则返回假
③不等 !=或
④不全等 !==
6.位运算符
| 按位与 | & | 均为1的位置1,其余置为0 |
| 按位或 | | | 有一个为1的位置为1,其余置为0 |
| 按位异或 | ^ | 不同的位置为1,其余置为0 |
| 按位非 | ~ | 1的位置为0,0的位置为1 |
| 左移 | 位向左移动n次,每移动一次相当于乘以2 | |
| 右移 | >> | 位向右移动n次,每移动一次相当于除以2 |
<span> <?<span php><span> <span>=123<span><span> <span>=321<span><span> <span> <span echo> '$a & $b='.(<span> & <span>).'<br>'<span><span> <span echo> '$a | $b='.(<span> | <span>).'<br>'<span><span> <span echo> '$a ^ $b='.(<span> ^ <span>).'<br>'<span><span> <span echo> '~$a='.(~<span>).'<br>'<span><span> <span echo> '$a<<4='.(<span><<4).'<br>'<span><span> <span echo> '$b>>4='.(<span>>>4).'<br>'<span><span> ?></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>
7.字符串运算符
(.)和(.=)以及{}
8.数组运算符(略)
9.类型运算符
类型运算符用instanceof常用来判断某个变量是否属于某个类的实例。
<span> <?<span php><span> <span class><span a><span> <span> <span><span> <span class><span b><span> <span> <span><span> <span> <span>=<span new><span a><span> <span var_dump>((<span> instanceof A));<span echo> '<br>'<span><span> <span var_dump>((<span> instanceof B));<span echo> '<br>'<span><span> ?></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>
10.错误控制运算符@











