Opcode Descriptions and Examples
PHP 手册

PRE_DEC

PHP code

<?php
/*
 * decrements variable indicated by value1 by 1 (before performing other operations) and stores in results
 * opcode number: 35
 */
--$a;
?>

PHP opcodes

Function name: (null)

Compiled variables: !0=$a

line#op fetchextreturn operands
60 PRE_DEC     !0
71 RETURN     1

Opcode Descriptions and Examples
PHP 手册