I explore various questions pertaining to a medley of topics. Initially the talk focuses on some undocumented fun to be had with identifiers. Attention next shifts to PHP’s comma operator and considers whether it even merits that designation. The main topic, which follows, derives from an example of some very questionable PHP logic. To avoid making a hasty, superficial judgment will entail discovering the hidden story behind PHP’s truth values. Particularly fascinating is the influence of other languages on their development and meaning. This segment also peers into PHP’s internal workings in a friendly fashion for non-C programmers. Novices as well as senior developers are all welcome; there’s plenty of code for everyone! Come learn about what surprises await you.

1. Surprise! It's PHP 
by
Sharon Lee Levy
[ unabridged PPT slideset ]

2. Surprise! It's PHP 
I. Introduction
II. What's in a Name?
III. The Mysterious
Comma
IV. Exploring Truth Values
V. Additional Thoughts
VI. Online Resources

3. Concluding someone … designed
PHP the way it is today. It has
history and heritage.
3
Common PHP Mistake
Flickr: by joanmaffeiart
Mike Wallner
See http://www.7php.com/php-interview-michael-wallner

4. Flickr: by derickrethans

5. ... PHP seems to almost read
your mind …
5
Flickr: by joanmaffeiart
Rasmus Lerdorf
See "The Early Days of PHP" interview

6. 6
Flickr: by joanmaffeiart

7. Artsy Hole
Flickr: by estherase
See Internals List: 3/2014

8. A valid variable name starts
with a letter or underscore…
8
…..
See Manual: Basics

9. 9
I ♥ UTF-8
<?php
$♥ = "love";
echo "I $♥ PHP!";
// I love PHP!
See php_in_webapps.pdf; StackOverflow: unicode-identifiers-function-names…,
JDN Interview of Andi Gutmans June 2014

10. 10
<?php
I ♥ UTF-8
const START= 0;
$len = mb_strlen( "♥", '8bit' ); // 3
echo mb_substr( "♥", START, $len ); // ♥
// otherwise: [e2 99 a5]

11. 11
<?php
I ♥ UTF-8
class Test{ const AB♥ = "alphabet"; }
$rc = new ReflectionClass("Test");
$t = array_keys( $rc->getConstants())[0];
$substr = substr( $t, -1,1 );
if ( $substr === "♥" ) {
trigger_error(""♥" in "$t"",E_USER_ERROR );
}
// [ PHP5.4 - 5.6 ]

12. 12
<?php
I ♥ UTF-8
class Test{ const AB♥ = "alphabet"; }
$rc = new ReflectionClass("Test");
$t = array_keys( $rc->getConstants())[0];
$substr = mb_substr( $t, -1,1 ); // PHP 5.6
if ( $substr === "♥" ) {
trigger_error(""♥" in "$t"", E_USER_ERROR);
}
// Fatal error: "♥" in "AB ♥" …

13. That's not a hole in the design.
Rasmus Lerdorf
Internals List 3/12/2014
13

14. Flickr: by comma?

15. The Mysterious Comma
15
echo_expr_list:
<?php
echo $var1, $var2, …
See Manual: Operator Precedence
 Left Associative
 Many Uses
 Has Least Precedence

16. The Mysterious Comma
16
echo_expr_list:
<?php
echo $var1, $var2, …
See PHP5.2 Changelog, lxr.php.net: echo_expr_list

17. 17
<?php
class Test {
const ALPHA = 1, BETA = 2, GAMMA = 3;
public $a = "apple", $b = "bread", $c = "candy";
// methods …
}
See StackOverflow: comma operator vs comma separator

18. 18
$a = 10, $b = 20, $c = 30;
See lxr.php.net: zend_language_parser.y

19. 19
list( $a, $b, $c ) = array( 10, 20, 30 );
var_dump( $a, $b, $c ); // 10, 20, 30

20. 20
Comma Operator
 C
 C++
 Perl
 PHP?
 JavaScript
See Wikipedia: Comma Operator

21. JavaScript's Comma
21
// JavaScript
var a = 2;
var b = 4;
var c = ( ++a, b * a );
// result: 12

22. not likely to be implemented...
bogussing.
Internals List 2/1/2002
22

23. 23
<?php
for (
$a = 3, $b = 4;
$a < $b;
$a++;
) {
$result = $a * $b;
}
var_dump( $result );
// int( 12 )
See doc.ic.ac.uk/lab/cplus/cstyle.html

24. 24
<?php
$a = 2;
$b = 4;
for ( ; ++$a, $a < $b; ) {
$res = $a * $b;
}
var_dump( $res );
// int( 12 )
See comma.html

25. Flickr: by derickrethans

26. 26
<?php
echo null < -1 && null == 0;
// true
See PHP: a fractal of bad design

27. 27
JavaScript's Null
// JavaScript
alert( null < -1 && null == 0 );
// false
See Ecma-262.pdf; StackOverflow: why-null-0-null-0-but-not-null-0

28. Flickr: by tajai

29. See StackOverflow uppercase-booleans-vs-lowercase-in-php and use-true-false-null;
29
TRUE, FALSE, and NULL
keywords should always be
fully uppercase.
Coding Standards: CodeIgniter 2.20

30. … true, false, null … should be
all lower case, as upper case is
reserved for constants.
Coding Standards: FuelPHP
30

31. Constants should always be …
uppercase … This includes …PHP
constants … TRUE, FALSE and
NULL…
Coding Standards: Drupal
31

32. … PHP constants true, false,
and null MUST be in lower case.
32
Coding Standard: PSR-2
See php-FIG: PSR_2 and 8/2014 discussion: http://tinyurl.com/mdasjak

33. … in PHP, they are not constants;
they are keywords mapping to
language constructs.
Matthew Weir O'Phinney
Project Lead, Zend Framework, 2012
33
See Programming PHP by Rasmus Lerdorf, et al; Manual: define()

34. To specify a boolean literal, use
the keywords TRUE or FALSE.
34
See Bug report #67228

35. To specify a boolean literal, use
the constants TRUE or FALSE.
35
See Manual: Booleans

36. 36
Technically … count more as
reserved keywords than
constants…
Nikita Popov
See Stackoverflow: NickiC 2/7/2014

37. …case insensitive, to be
downwards compatible and
consistent with other languages…
Zeev Suraski
37
See Internals List: 5/8/98

38. 38
Flickr: by thebittenword.com

39. Proof in the Pudding …
39
TRUE, FALSE, NULL
 Usable as Identifiers
 Ea. Has a Data Type
See Manual: Reserved Constants, Language: Constants, Zend API: Hacking the Core of PHP;
PHP Language Spec; 3v4l.org: V3H2n; Internals List: 7/16/2004

40. 40
PERL Legacy
Flickr: by ♫ Desmatron ♫

41. PERL Legacy
… truth value of expressions
in PHP is calculated in a
similar way to perl.
41
Zero
Zero
C false
JavaScript false
Perl false
PHP false
Python false
Ruby true
LISP true
Scheme true
 False: 0
 True: !0
 False: "" and "0"
 True : 1 [<,>,<=,=>,==]
PHP 3.0b4: lang-const.sgml

42. 42
PERL Legacy
 False: 0
 True: !0
Perl
 False: "" and "0"
 True : 1 [<,>,<=,=>,==]
See 3v4l.org: TrT4l; PerlMonks; What is true and false …

43. 43
PERL Legacy
Zero
Zero
C false
JavaScript false
Perl false
PHP false
Python false
Ruby true
LISP true
Scheme true
See StackOverflow: why-treat-0-as-true-in-ruby; is-false-0-and-true-1-in-python…

44. True/False as C Macros
44
#define TRUE 261
#define FALSE 262

45. True/False as Keywords
45
PHP3 Beta5 (2/98)
PHP_TRUE 1
PHP_FALSE ""
See Internals List 2/25/98 and bug report #354

46. True/False as Keywords
46
PHP3 Beta5 (2/98)
<IN_PHP>"FALSE" {
phplval->value.strval = empty_string;
phplval->strlen = 0;
phplval->type = IS_STRING;
return PHP_FALSE;
}
<IN_PHP>"TRUE" {
phplval->value.lval = 1;
phplval->type = IS_LONG;
return PHP_TRUE;
}
See PHP3.0b6: language_scanner.lex, parser.h, language-parser.tab.c,
configuration-parser.tab.c (and v.3.0, too)

47. True/False as Keywords
Made chown(), chgrp() and
chmod() return TRUE/FALSE
instead of 0/-1.
PHP 3.0b5 ChangeLog
47
PHP3 Beta5 (2/98)
See Internals List 2/25/98

48. 48
PHP3 Constant
 name: true, false, …
 name_len
 value
value (pval)
value: [1, ""]
type: [IS_LONG, IS_STRING]
See Internals List 5/8/98, 7/1/98 ; PHP3 constants.[ch],
php.h; PHP3 Manual: Language constructs

49. Until PHP3rc5 …
$a = foo;
// Notice: 'foo' is not a valid constant[ PHP3rc5+ ]
// Notice: Use of undefined constant [ PHP4.3+ ]
$a = "foo"; // mandatory: quoted
49
See Internals List: 5/24/98; PHP3: language-parser.tab.c, line 2642

50. 50
Design & Consequences
if ("5") {
echo "Would print";
}
if ("5"==TRUE) {
echo "Would not print";
}
Zeev Suraski
General List: 7/1/98
See lang-const.html

51. 51
PHP4 Reinvention
zend_constant
See PHP 4: zend_constants.[ch], zend.h
value
value (zval)
value: [1, 0]
type: IS_BOOL

52. 52
PHP4 Reinvention
<?php
var_dump( (bool) 1);
// bool( true )
See Andi Gutmans commit 4/71999: zend_constants.c; Extending and Embedding PHP by Sara Golemon, p
165; Internals List: 6/4/2000

53. 53
<ST_IN_SCRIPTING>"NULL" {
ZVAL_NULL(zendlval);
return T_NULL;
}
<ST_IN_SCRIPTING>"FALSE" {
ZVAL_FALSE(zendlval);
return T_FALSE;
}
<ST_IN_SCRIPTING>"TRUE" {
ZVAL_TRUE(zendlval);
return T_TRUE;
}
Deja Vu?
See php-cvs: 7/16/2004, Internals List: 07/16/2004, lxr.php.net: zend_language_scanner.l
(History: Marcus Boerger 7/16/2004);

54. Improved Booleans
54
PHP5.6:
Z_LVAL_P(__z) = ((b) != 0);
Z_LVAL_P(__z) = IS_BOOL;
PHPNG:
Z_TYPE_INFO_P(z) = (b) ? IS_TRUE :
IS_FALSE;
See PHP5.6 and PHPNG: zend_constants.h, zend_constants.c, zend_API.h;
PHPNG: zend_types.h; also wiki.php.net: phpng; Internals List 11/10/2013

55. … I misunderstood the expression
evaluation of NULL/FALSE of PHP
for my entire PHP life 
Yasuo Ohgaki
Internals List 11/10/2013
See blog.ohgaki.net: php-bool-null ( use Google translate); zend types.h: zval_bool and
zend_vm_execute.h: isset/empty handler
55

56. …please, don't make php
programmers go berserk :)
56
Michal Vitecek
See bug report: #4805

57. 57
<?php
echo ( !1 ); // PHP3: 0
echo ( !1 ); // PHP4:
See Internals List: 6/4/2000; PHP3: language_parser.y and operators.c

58. ZEND_API int boolean_not_function(zval *result, zval *op1)
{
zval op1_copy;
zendi_convert_to_boolean(op1, op1_copy, result);
58
result->type = IS_BOOL;
result->value.lval = !op1->value.lval;
return SUCCESS;
}
See PHP4: zend_operators.c

59. 59
… echo nothing at all?
That's a bit Perlish for
me!
John Sutton
Internals List, 7/1998

60. 60
Invisible False
<?php echo false;
Opcode Return Value Operands
ECHO false

61. Invisible False
ZEND_ECHO_SPEC_CONST_HANDLE
R
61
zend_print_variable()
zend_print_zval()
zend_print_zval_ex()
See lxr.php.net: zend_vm_execute.h

62. 62
Invisible False
zend_print_zval_ex():
zend_make_printable_zval()
/* optimize away empty strings */
return 0
write_func()
See lxr.php.net: zend.c#311; also: How-to-add-new-syntactic-features-to-PHP.html by
Nikita Popov

63. false has to be an empty string
to correctly evaluate to false.
63
See Manual: Strings
Rasmus Lerdorf
Bug Report #49097

64. 64
"0" <=> false <=> "0"
"" => false => "0"
See StackOverflow: why-doesnt-php-print-true-false

65. 65
"" <=> false <=> ""
"0" => false => "" => 0 => "0"
See StackOverflow: php-get-bool-to-echo-false-when-false

66. Flickr: by Tracey Stephens

67. 67
<?php
for ( $i = 1; ;$i++ ) {
if ($i > 10) {
break;
}
print $i; // 12345678910
}
See PHP-3.0b4: lang-const.sgml, StackOverflow: what-does-for-mean, PHP5.6: zend_language_parser.y

68. 68
for_expr:
/* empty */ {
$$.op_type = IS_CONST;
Z_TYPE($$.u.constant) = IS_BOOL;
Z_LVAL($$.u.constant) = 1;
}
See PHP-3.0b4: lang-const.sgml, StackOverflow: what-does-for-mean, PHP5.6: zend_language_parser.y

69. 69
<?php
$_POST[ "quantity" ] = "0";
if ( !empty( $_POST[ "quantity" ] ) ) {
echo "It's not empty"; // PHP 3
} else {
echo "It's empty"; // PHP 4
}
See Internals List 5/11/2000, Manual: empty PHP3 and PHP4; bug report #: 2088

70. 70
empty() considers "0" as
non-empty, a value that …
may come from an HTML
form.
See Internals List 5/11/2000, Manual: empty PHP3 and PHP4; bug report #: 2088

71. 71
<?php
var_dump( "", "0" );
// string(0) "", string(1) ""
var_dump( (bool) "" );
// bool(false)
var_dump( (bool) "0" );
// bool(true)
var_dump( (bool) "0" );
// bool(false)
See Manual: Booleans, bug report # 39904

72. 72
Boolean "0"
Perl false
PHP false
C true
Python true
Ruby true
JavaScript true/false
See Manual: Booleans, bug report #39904, perlmonks.org: what is true and false in perl,
codepag.org: ScNhuOqY, 5zOu4NjN , Internals List: 2/25/98, 5/11/98, PHP3 ChangeLog: 5/11/98

73. 73
JavaScript's "0"
// JavaScript
if ("0") alert(""0" is true"); // true
if ("0" == false) alert(""0" is false"); // true
See StackOverflow: why-does-0-a-b-behave-different-than-0-true-a-b

74. "0" is no longer considered
false …
74
-
Zeev Suraski
See Internals List: 2/25/98, 5/11/98 and PHP3 ChangeLog: 5/11/98

75. 75
…we're still thinking whether
"0" should be considered false
Andi & Zeev
See Internals List: 2/25/98, 5/11/98 and PHP3 ChangeLog: 5/11/98

76. "" (string,false) <=> 0 (int, false) <=> "0"(string,true)
76
See Internals List: 2/25/98, 5/11/98 and PHP3 ChangeLog: 5/11/98

77. ***NOTE*** Changed "0" to
mean FALSE again
77
See Internals List: 2/25/98, 5/11/98 and PHP3 ChangeLog: 5/11/98

78. 78
<?php
echo empty( "" ); // 1
echo empty( "0" ); // 1
echo (int) ( "" == "0" ); // 0
See 3v4l.org: U0G6L#v430, Manual: empty, Internals List: 8/20/2014

79. 79
<?php
$a = "0.0";
$b = 0.0;
var_dump( $a == $b ); // true
var_dump( empty( $a ) ); // false
See Bug report #: 60402 and The Manual; pickingUpPerl_5.html;
PHP4 Manual: migration4.empty.html

80. 80
<?php
$items = false;
echo count( $items ); // 1
$it = new EmptyIterator;
var_dump( count( $it ) ); // 1
See lxr.php.net: array.c, Bug reports #: 46322 and #: 60577

81. 81
Counts all elements in an
array, or something in an
object
PHP5 Manual
See lxr.php.net: array.c, Bug reports #: 46322 and #: 60577

82. Returns the number of elements
in var, … typically an array …
anything else will have one
element ...
82
PHP3 Manual
See lxr.php.net: array.c, Bug reports #: 46322 and #: 60577

83. 83
switch (Z_TYPE_P(array)) {
case IS_NULL:
RETURN_LONG(0);
break;
case IS_ARRAY: [snipped]
case IS_OBJECT:
/* handler defined? */
/* If Countable, call count() method */
default:
RETURN_LONG(1);
break;
}
See lxr.php.net: array.c, Bug reports #: 46322 and #: 60577

84. Flickr: by Steve Mynett

85. Dec 28, 1999 (Thies Arntzen) new constant SQL_NULL
PHP4.0b4: (Feb 2000)
Added new NULL constant (Zeev, Zend Engine)
85
About Null
c.value.value.lval = 0;
c.value.type = IS_LONG;
See Thies Arntzen's Commit, PHP4 Changelog; PHP 4: zend_constants.c; bug report: #67562

86. 86
About NULL
zend_constant
value
value (zval)
vvaalluuee:: [[ uunnsseett ]]
ttyyppee:: IISS__NNUULLLL
null is not a value, was never
meant to be a value, and won't
be a value.
Zeev Suraski
Internals List 8/17/2003
See PHP4.0b4 Changelog; PHP 4: zend_constants.c; bug report: #67562

87. 87
<?php
echo (int) null;
// 0
See lxr.php.net: (PHP5.2) zend_operators.c annotated and history.

88. 88
// Dec. 31, 1999 – introduced IS_UNSET - Zeev Suraski
convert_to_long_base( zval *op, int base ):
switch (op->type) {
case IS_UNSET:
op->value.lval = 0;
break;
See lxr.php.net: (PHP5.2) zend_operators.c annotated and history.

89. 89
// Jan 4, 2000: IS_UNSET => IS_NULL - Andi Gutmans
convert_to_long_base( zval *op, int base ):
switch (op->type) {
case IS_NULL:
op->value.lval = 0;
break;
See lxr.php.net: (PHP5.2) zend_operators.c annotated and history.

90. 90
<?php
$a = "apple";
$a = null;
echo isset( $a ); // false
unset( $a );
echo isset( $a ); // false
echo isset( $b ); // false
See Internals List: 7/3/2014

91. 91
<?php
// null detection:
echo isset( $var ); // false
echo empty( $var ); // true
See Internals List: 7/3/2014; Nikita Popov RFC: Abstract Syntax Tree

92. isset( $var ) && $var == NULL // Internals List
!isset($var) || $var == false // The Manual
ZVAL_BOOL(&EX_T(opline->result.var).tmp_var, 1);
92
<?php
/* if (opline->extended_value & ZEND_ISEMPTY) */ {
if (!isset || !i_zend_is_true(*value)) {
See Internals List: 7/3/2014; Nikita Popov RFC: Abstract Syntax Tree

93. 93
<?php
// null detection:
echo is_null( $var ); // true, but…
echo (null === $var ); // ditto
See Internals List: 7/3/2014; Nikita Popov RFC: Abstract Syntax Tree

94. 94
# Perl:
unless( defined( $var ) ) { # unless == if !
print "$var is undefined";
}
See Internals List: 7/3/2014; Nikita Popov RFC: Abstract Syntax Tree

95. 95
<?php
See StackOverflow: Eisberg
$n = null;
var_dump( array_key_exists( 'n',
get_defined_vars() ) );
// true

96. 96
<?php
See StackOverflow: Eisberg
$n = null;
unset( $n );
var_dump( array_key_exists( 'n',
get_defined_vars() ) );
// false

97. 97
<?php
$count = count( get_defined_vars() );
$myvar = null;
$recount = get_defined_vars();
var_dump( array_slice( $recount, $count + 1) );
// array(1) { ["myvar"]=> NULL }
See StackOverflow: Eisberg

98. 98
<?php
See Internals List 6/5/2005
$count = null;
$count++;
var_dump( $count ); // int(1)
$count--;
var_dump( $count ); // null

99. 99
// int increment_function
case IS_BOOL:
op1->value.lval++;
op1->type = IS_LONG;
break;
case IS_NULL:
op1->value.lval = 1;
op1->type.lval = IS_LONG;
// int decrement_function
case IS_BOOL:
op1->value.lval--;
op1->type = IS_LONG;
break;
case IS_NULL:
op1->value.lval = -1;
op1->type = IS_LONG;
Excerpted from Johannes Schlueter's Patch; see also Tjerk Meesters'
RFC:Normalize increment and decrement operators

100. 100
// JavaScript:
var m = null, n = null;
alert( ++m ); // 1
alert( --n ); // -1
var e = true, f = false;
alert( ++e ); // 2
alert( --f ); // -1

101. 101
<?php
// * Sum byte values from position x in $str
function sum( $str, $x ) {
$sum = 0;
for ( $max = strlen( $str );
$x < $max;
++$x ) {
$sum += ord( $str[ $x ] );
}
return $sum;
}
$str = 'Hello, Dolly';
echo sum( $str, strpos( $str, 'F' ) ); // typo: sh/b 'D'
See Internals List 6/5/2005, Johannes Schlueter's Patch and Tjerk
Meesters' RFC: Normalize increment and decrement operators

102. Compare NULL & Any
102
 Convert both sides to bool
 FALSE < TRUE
See Internals List 11/10/2013; Manual: comparison operators: PHP5.3 and PHP5.5

103. Compare NULL & Any
103
<?php
echo null < -1;
echo false < true;
See Internals List 11/10/2013; Manual: comparison operators: PHP5.3 and PHP5.5

104. Code Compliance?
104
<?php echo null < -1;
Opcode Return Value Operands
IS_SMALLER ~0 null, -1

105. 105
Is_Smaller
ZEND_IS_SMALLER_SPEC_CONST_CONST_HANDLE
R
ZVAL_BOOL(result,
fast_is_smaller_function:
compare_function(result, null, -1)
…
)
See PHP5.6: zend_vm_execute.h, zend_operators.h,

106. PHP4: Compare_Function
/* op1->type == IS_NULL */
zendi_convert_to_boolean(op1, op1_copy, result);
zendi_convert_to_boolean(op2, op2_copy, result);
result->type = IS_LONG;
result->value.lval = NORMALIZE_BOOL(
op1->value.lval-op2->value.lval
);
106
return SUCCESS;
See zend_operators.c, PHP4

107. PHP4: Compare_Function
/* op1->type == IS_NULL */
zendi_convert_to_boolean(op1, op1_copy, result);
zendi_convert_#define to_NORMALIZE_boolean(op2, op2_BOOL(copy, n)
result);
result->type = IS_LONG;
result->value.lval = NORMALIZE_BOOL(
op1->value.lval-op2->value.lval
);
107
return SUCCESS;
((n) ? (((n)>0) ? 1 : -1) : 0)
See zend_operators.c, PHP4

108. PHP5: Compare_Function
if (Z_TYPE_P(op1) == IS_NULL) {
zendi_convert_to_boolean(op2, op2_copy, result);
ZVAL_LONG(result, Z_LVAL_P(op2) ? -1 : 0);
return SUCCESS;
}
108
* See lxr.php.net: PHP_5_6/Zend/zend_operators.c#1593

109. 109
Is_Smaller Result
ZEND_IS_SMALLER_SPEC_CONST_CONST_HAND
LER
ZVAL_BOOL(result,
fast_is_smaller_function:
compare_function(result, null, -1)
return Z_LVAL_P(result) < 0
)
See PHP5.6: zend_vm_execute.h, zend_operators.h,

110. 110
Flickr: by fxalau

111. 111
<?php
var_dump( null == false );
var_dump( false == 0 );
var_dump( null == 0 );
// true

112. Internals of Equality
112
<?php null == 0; // True
Opcode Return Value Operands
IS_EQUAL ~0 null, 0
Recommended reading: Anatomy of Equals by A. Ferrara

113. compare_function(result, null, 0);
…
113
Is_Equal
ZEND_IS_EQUAL_SPEC_CONST_CONST_HANDLER
ZVAL_BOOL( result,
fast_equal_function():
)
See lxr.php.net: PHP_5_6/Zend/zend_vm_execute.h#3475

114. PHP5: Compare_Function
if (Z_TYPE_P(op1) == IS_NULL) {
zendi_convert_to_boolean(op2, op2_copy, result);
ZVAL_LONG(result, Z_LVAL_P(op2) ? -1 : 0);
return SUCCESS;
}
114
See lxr.php.net: PHP_5_6/Zend/zend_operators.c#1593; PHP5.2: zend_operators.c

115. compare_function(result, null, 0);
return Z_LVAL_P(result) == 0;
115
Is_Equal
ZEND_IS_EQUAL_SPEC_CONST_CONST_HANDLER
ZVAL_BOOL( result,
fast_equal_function():
)
See lxr.php.net: PHP_5_6/Zend/zend_vm_execute.h#3475

116. 116

117. Resources
 3v4l.org
 codepad.org
 lxr.php.net
 markmail.org: "PHP Internals List"
 museum.php.net
 slevy1.wordpress.com