Opcode Descriptions and Examples
PHP Manual

ADD_CHAR

PHP code

<?php
/*
 * add character value2 to string value1 and store in result
 * opcode number: 54
 */
echo "hello\ world";
?>

PHP opcodes

Function name: (null)

Compiled variables: none

line#op fetchextreturn operands
60 ECHO     'hello%5C+world'
71 RETURN     1

Opcode Descriptions and Examples
PHP Manual