of course this should be clear, but i think it has to be mentioned espacially:
AND is not the same like &&
for example:
<?php $a && $b || $c; ?>
is not the same like
<?php $a AND $b || $c; ?>
the first thing is
(a and b) or c
the second
a and (b or c)
'cause || has got a higher priority than and, but less than &&
of course, using always [ && and || ] or [ AND and OR ] would be okay, but than you should at least respect the following:
<?php $a = $b && $c; ?>
<?php $a = $b AND $c; ?>
the first code will set $a to the result of the comparison $b with $c, both have to be true, while the second code line will set $a like $b and THAN - after that - compare the success of this with the value of $c
maybe usefull for some tricky coding and helpfull to prevent bugs :D
greetz, Warhog
연산자
Table of Contents
연산자는 하나 이상의 값(또는, 프로그래밍 은어로 표현)을 받아서 다른 값을 산출합니다. (그러므로 구조 자체는 표현이 됩니다) 그러므로 (print처럼) 값을 반환하는 함수나 구조를 연산자로 생각할 수 있고, (echo처럼) 아무것도 반환하지 않는 것을 다른 것으로 생각할 수 있습니다.
세 종류의 연산자가 있습니다. 첫번째는 하나의 값에만 작용하는 일항 연산자입니다. 예를 들면, !(부정 연산자)나 ++(증가 연산자)가 있습니다. 두번째는 이항 연산자로 불립니다; 이 종류는 PHP가 지원하는 대부분의 연산자에 해당합니다. 목록은 아래의 연산자 우선권 섹션에 있습니다.
세번째는 삼항 연산자입니다: ?:. 이것은 세번째에 의존해서 두 표현 중 하나를 선택하는 데 사용합니다. 삼항 연산자를 괄호로 감싸는 건 매우 좋은 생각입니다.
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User Contributed Notes 4 notes
Anonymous ¶
20 years ago
anisgazig at gmail dot com ¶
4 years ago
Operator are used to perform operation.
Operator are mainly divided by three groups.
1.Uniary Operators that takes one values
2.Binary Operators that takes two values
3.ternary operators that takes three values
Operator are mainly divided by three groups that are totally seventeen types.
1.Arithmetic Operator
+ = Addition
- = Subtraction
* = Multiplication
/ = Division
% = Modulo
** = Exponentiation
2.Assignment Operator
= "equal to
3.Array Operator
+ = Union
== = Equality
=== = Identity
!= = Inequality
<> = Inequality
!== = Non-identity
4.Bitwise Operator
& = and
^ = xor
| = not
<< = shift left
>> = shift right
5.Comparison Operator
== = equal
=== = identical
!= = not equal
!== = not identical
<> = not equal
< = less than
<= less than or equal
> = greater than
>= = greater than or equal
<=> = spaceship operator
6.Execution Operator
`` = backticks
7.Error Control Operator
@ = at sign
8.Incrementing/Decrementing Operator
++$a = PreIncrement
$a++ = PostIncrement
--$a = PreDecrement
$a-- = Postdecrement
9.Logical Operator
&& = And
|| = Or
! = Not
and = And
xor = Xor
or = Or
10.string Operator
. = concatenation operator
.= concatenating assignment operator
11.Type Operator
instanceof = instanceof
12.Ternary or Conditional operator
?: = Ternary operator
13.Null Coalescing Operator
??" = null coalescing
14.Clone new Operator
clone new = clone new
15.yield from Operator
yield from = yield from
16.yield Operator
yield = yield
17.print Operator
print = print
yasuo_ohgaki at hotmail dot com ¶
23 years ago
Other Language books' operator precedence section usually include "(" and ")" - with exception of a Perl book that I have. (In PHP "{" and "}" should also be considered also). However, PHP Manual is not listed "(" and ")" in precedence list. It looks like "(" and ")" has higher precedence as it should be.
Note: If you write following code, you would need "()" to get expected value.
<?php
$bar = true;
$str = "TEST". ($bar ? 'true' : 'false') ."TEST";
?>
Without "(" and ")" you will get only "true" in $str.
(PHP4.0.4pl1/Apache DSO/Linux, PHP4.0.5RC1/Apache DSO/W2K Server)
It's due to precedence, probably.
figroc at gmail dot com ¶
16 years ago
The variable symbol '$' should be considered as the highest-precedence operator, so that the variable variables such as $$a[0] won't confuse the parser. [http://www.php.net/manual/en/language.variables.variable.php]
