Detailed explanation of commonly used operators and operation symbols in PHP_PHP Tutorial

/*Operation symbols (PHP) operation symbols
*
* According to the operation symbol function, it is divided into:
* 1. Arithmetic operators + - * / % ++ --
* 2. String operators. Connection operators
* 3. Assignment operator = += -= *= /= %= .=
* 4. Comparison operators > < >= <= == === != <> !==
* Comparison operators---conditional operators---relational operators
* There is only one result after comparison: boolean true false
* === When comparing, not only the content is required to be the same, but also the type is required to be the same
* !== When comparing, the contents are not the same, and the types are also required
* 5. Logical operators && or and || or or ! or not
* Logical operators can only operate on bool type values ​​and return bool type values ​​
* 6. Bitwise operators & | ^ ~ << >> >>>
* 7. Other operators ? : `` @ => -> :: & $
* `` Used to execute the operating system kernel
* @ Used to block error messages
* It is recommended to use "()" to change the priority of expressions
*
* % has two purposes: integer division operation; control range, do not use decimals or negative numbers
* % Convert the numbers on both sides of the operator to integers and then divide them to find the remainder.
*/

//Use % symbol to determine leap year

$year=2011;
if(($year%4==0 && %year%100!=0) || $year%400=0)
{
echo "run nian";
}
else
{
echo " not run nian";
}

// ++ --Usage of symbols
$a=10;
$a++; //$a=$a+1; Use variables first, then increment by 1
++$a; //$a=$a+1; First increment by 1, then use variable
$a--; //$a=$a-1; Use the variable first, then decrement it by 1
--$a; //$a=$a-1; Decrement it by 1 first, then use the variable
echo $a; //The result is 10

//++ -- Differences in operations

$a=10;
$b=$a++;//b=10,a=11
$c=--$b;//c=9,b=9
$d=$c++ + ++$c; //d=20,c=11
$e=$d-- - --$d; //d=18,e=2
echo $d;

//Usage of string operator .
$name="tom";
$age=27;
$height=1.75;
echo "My name is: {$name} My age is: {$age} My height is: {$height} meters
";
echo 'My name is: '.$name.' My age is: '.$age.' My height is: '.$height.'m'.'
';
echo "$age=".$age; //$age=27

echo "My name is: {$name} My age is: {$age} My height is: {$height} meters
";//Usage of assignment operator

$a=10;
$a+=10; //$a=$a+10;
$a-=10; //$a=$a-10;
$a*=10; //...
$a/=10; //...
$a%=10; //$a=$a%10;
$a.="abc";//$a=$a."abc";
echo $a;
$str='

';
$str.='';
$str.='';
$str.='';
$str.='

';
$str.='

';
echo $str;//Output a table

//Comparison operator
var_dump(15>6);//return bool(true)
$a=15;
if(15==$a)
{
echo "a=15";
}
else
{
echo "a!=15";
}

//Use of logical operators

var_dump(true && true);//true
var_dump(true && false);//false
var_dump(true || false);//true
var_dump(!true);//false
var_dump(!false);//true
//Determine username and password
$username="admin";
$password="123456";
$email="290080604@qq.com";
if($username=="admin" && $password="123456")
{
echo "Username and password are correct";
}
if($username=="" || $password=="" || $email=="")
{
echo "None of them can be empty";
}

//bit operator
$a=20; //00010100
$b=30; // 00011110
/*
* 20 00010100
* 30 00011110 &
*----------------------------------
* 00010100
*
*/
$c=$a & $b;
echo $c;

/*Additional, & | can also be used for logical operations
* Short circuit problem of && and ||:
* When && is performing an operation, if the previous number is false, then whether the following number is true, the entire expression is false, so the following operands will not be executed;
* ||During operation, if the previous number is true, then whether the following number is false, the entire expression is true, so the following operands will not be executed;
* However, when & or | are operated, both sides will be executed
*/
$a=10;
if($a>5 || $a++<100){}
echo $a;//output 10
$b=10;
if($b>5 | $b++<100){}
echo $b;//output 11

/*
The concept of bit: A bit is composed of 8 binary numbers (for example, 00000000),
A byte consists of 8 bits, so there are 32 binary numbers.

Original code: The highest bit uses 0 to represent positive numbers and 1 to represent negative numbers

+7 00000111
-7 10000111

Negative code: If a number is positive, its complement is the same as the original code;
If a number is negative, the sign bit is 1, and the remaining bits are the inversion of the original code;
+7 00000111
-7 11111000

+0 00000000
-0 11111111

Complement code: If a number is positive, its complement and inverse code are the same as the original code
If a number is negative, its complement = one's complement + 1, and the highest overflow bit is removed
       
-7 Original code 10000111 Reverse code 11111000
                                                     Complement code 11111001
                                                                         Given the complement of a negative number, convert it to decimal.
1. Let me disprove everyone first
2. Convert it to decimal number
3. Add the negative sign and subtract 1.

Example: complement code 11111010

Negation 00000101

              4+1=5
-5-1=-6
 
Bit operators:
& Bitwise AND |Bitwise OR ^Bitwise XOR ~Bitwise negation

Example: Bitwise AND 01101101

                 &00110111

                  00100101
Conclusion: Only 1 1 is 1.
Bitwise OR 01101101
|00110111
                 01111111
Conclusion: Only 0 0 is 0.
​​Bitwise XOR 01101101
                ^00110111
                 01011010
Conclusion: It is 1 when there are only 1 0 or 0 1. (It can also be understood as 1 (true) in different states)
               Bitwise negation ~00110111
11001000
Conclusion: Change 0 to 1 and 1 to 0

Shift operator:
Left shift:<< Signed right shift:>> Unsigned right shift:>>>

Example: Number x x<<2 x>>2 x>>>2
17 00010001 01000100 00000100 00000100
-17 11101111 10111100 11111011 00111011
Conclusion: Positive numbers are padded with 0 when moving left and right, negative numbers are padded with 0 when moved left, signed right is padded with 1, and unsigned is padded with 0


*/

//Use of other operators
$a=10;
$b=$a>5 ? $a : 5;//Ternary operator, if true $b=$a otherwise $b=5
echo $b;

//Use `` to execute operating system shell commands
$str=`ipconfig /all`;
echo '

';<br>
echo $str;<br>
echo '

';

?>

This section lists the various operators used in PHP:

Arithmetic operators

Operator

Description

Example

Results

+

Addition

x=2

运算符	说明	例子	结果
+	Addition	x=2 x+2	4
-	Subtraction	x=2 5-x	3
*	Multiplication	x=4 x*5	20
/	Division	15/5 5/2	3 2.5
%	Modulus (division remainder)	5%2 10%8 10%2	1 2 0
++	Increment	x=5 x++	x=6
--	Decrement	x=5 x--	x=4

x+2

4

-

Subtraction

x=2 5-x

3

*

Multiplication

x=4

x*5

20

/

Division

15/5 5/2

3 2.5

%

Modulus (division remainder)

5%2 10%8

10%2

1

运算符	说明	例子
=	x=y	x=y
+=	x+=y	x=x+y
-=	x-=y	x=x-y
*=	x*=y	x=x*y
/=	x/=y	x=x/y
.=	x.=y	x=x.y
%=	x%=y	x=x%y

2 0

++

Increment

x=5

x++

x=6

--

Decrement

x=5 x--

x=4

Assignment operator

运算符	说明	例子
==	is equal to	5==8 returns false
!=	is not equal	5!=8 returns true
>	is greater than	5>8 returns false
<	is less than	5<8 returns true
>=	is greater than or equal to	5>=8 returns false
<=	is less than or equal to	5<=8 returns true

<🎜> <🎜> <🎜> <🎜> <🎜><🎜>Comparison operators<🎜><🎜> <🎜> <🎜>

逻辑运算符

http://www.bkjia.com/PHPjc/632287.htmlwww.bkjia.comtruehttp://www.bkjia.com/PHPjc/632287.htmlTechArticle

?php教程 /*运算符号（PHP）操作符号 * *按运算符号功能分为： *一、算术运算符 + - * / % ++ -- *二、字符串运算符 . 连接运算符 *三、赋值运算...

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运算符

说明

例子

&&

and

x=6
y=3

运算符	说明	例子
&&	and	x=6 y=3 (x < 10 && y > 1) returns true
||	or	x=6 y=3 (x==5 || y==5) returns false
!	not	x=6 y=3 !(x==y) returns true

(x < 10 && y > 1) returns true

||

or

x=6
y=3 (x==5 || y==5) returns false

!

not

x=6
y=3

!(x==y) returns true