Chapter 4_PHP Basic Syntax (2)_PHP Tutorial

1. Declaration of constants

In PHP, define constants using the define() function

　2.Magic constants

	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

The test code is as follows:

<span 1</span> <?<span php
</span><span 2</span>     <span function</span><span  sayHello(){
</span><span 3</span>         <span echo</span> '<p>the name of this function is:'.<span __FUNCTION__</span><span ;
</span><span 4</span> <span     }
</span><span 5</span>     
<span 6</span>     <span echo</span> '<p>这是第'.<span __LINE__</span>.'行。'<span ;
</span><span 7</span>     <span echo</span> '<p>本文件的绝对路径为:'.<span __FILE__</span><span ;
</span><span 8</span> <span     sayHello();
</span><span 9</span>     ?>

　3. Reference assignment

Use different variable names to access the same variable content. When the value of one variable changes, the other one also changes.

　4. Logical operators

Not with && or ||! ​Exclusive OR xor

<span 1</span> <?<span php
</span><span 2</span>     <span $a</span>=<span true</span><span ;
</span><span 3</span>     <span $b</span>=<span false</span><span ;
</span><span 4</span>     
<span 5</span>     <span var_dump</span>(<span $a</span> && <span $b</span>);<span echo</span> '<br>'<span ;
</span><span 6</span>     <span var_dump</span>(<span $a</span> || <span $b</span>);<span echo</span> '<br>'<span ;
</span><span 7</span>     <span var_dump</span>(<span $a</span> xor <span $b</span>);<span echo</span> '<br>'<span ;
</span><span 8</span>     <span var_dump</span>(!<span $a</span>);<span echo</span> '<br>'<span ;
</span><span 9</span>  ?>

5. Comparison operator

　①Equal　==　$a==$b　When the value of $a is equal to the value of $b, it returns true, otherwise it returns false

　②Congruent=== $a===$b When the value of $a is equal to the value of $b, and the types of $a and $b are also equal, then return true, otherwise return False

　③No wait! =or<>

　④Not equal! ==

　6. Bit operators

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  1</span> <?<span php
</span><span  2</span>     <span $a</span>=123<span ;
</span><span  3</span>     <span $b</span>=321<span ;
</span><span  4</span>     
<span  5</span>     <span echo</span> '$a & $b='.(<span $a</span> & <span $b</span>).'<br>'<span ;
</span><span  6</span>     <span echo</span> '$a | $b='.(<span $a</span> | <span $b</span>).'<br>'<span ;
</span><span  7</span>     <span echo</span> '$a ^ $b='.(<span $a</span> ^ <span $b</span>).'<br>'<span ;
</span><span  8</span>     <span echo</span> '~$a='.(~<span $a</span>).'<br>'<span ;
</span><span  9</span>     <span echo</span> '$a<<4='.(<span $a</span><<4).'<br>'<span ;
</span><span 10</span>     <span echo</span> '$b>>4='.(<span $b</span>>>4).'<br>'<span ;
</span><span 11</span> ?>

　7. String operators

　(.) and (.=) and {}

8. Array operators (omitted)

　9. Type operator

The type operator instanceof is commonly used to determine whether a variable belongs to an instance of a certain class.

<span  1</span> <?<span php
</span><span  2</span>     <span class</span><span  A{
</span><span  3</span>         
<span  4</span> <span     }
</span><span  5</span>     <span class</span><span  B{
</span><span  6</span>         
<span  7</span> <span     }
</span><span  8</span>     
<span  9</span>     <span $myclass</span>=<span new</span><span  A;
</span><span 10</span>     <span var_dump</span>((<span $myclass</span> instanceof A));<span echo</span> '<br>'<span ;
</span><span 11</span>     <span var_dump</span>((<span $myclass</span> instanceof B));<span echo</span> '<br>'<span ;
</span><span 12</span> ?>

　10. Error control operator@

http://www.bkjia.com/PHPjc/626587.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/626587.htmlTechArticle1. Declaration of constants In PHP, define constants using the define() function 2. Magic constants return files The current line number in __FILE__ returns the full path and file name of the file __DIR...