PHP執行這段代碼會經過如下4個步驟(確切的來說,應該是PHP的語言引擎Zend)

1.Scanning(Lexing) ,將PHP代碼轉換為語言片段(Tokens)

2.Parsing, 將Tokens轉換成簡單而有意義的表達式

3.Compilation, 將表達式編譯成Opocdes

4.Execution, 順次執行Opcodes,每次一條,從而實現PHP腳本的功能.

token_get_all()

將一段PHP代碼 Scanning成Tokens；

var_dump(token_get_all('<?php echo "Hello World"; ?>'));

Array(

[0] => Array(

[0] => 376

[1] => <?php

[2] => 1 )

[1] => Array(

[0] => 319

[1] => echo

[2] => 1 )

[2] => Array(

[0] => 379

[1] =>

[2] => 1 )

[3] => Array(

[0] => 318

[1] => "Hello World"

[2] => 1 )

[4] => ;

[5] => Array(

[0] => 379

[1] =>

[2] => 1 )

[6] => Array(

[0] => 378

[1] => ?>

[2] => 1 )

)