Learning notes for PHP operators

operator symbol (action symbol)

The function of the operation symbol is divided into

One: Arithmetic operators (+-*/% + +-)
%//has two purposes: integer operation, control range operation (do not use decimal, and do not use negative numbers)
Turns the numbers on both sides to integers and then divides them.

Example:
Code:
$year =?;
if ($year%4==0 && $year%100!=0) | | $year%400==0) {
echo "is a leap year";
}else{
echo "is not a leap year";
}
Code:
$a = 109009;
echo $a% 10;

+ + and-

Example:
Code:
$a = 10;

$a + +; $a = $a +1 first with a variable in the self increase 1
+ + $a; $a = $a +1 First use the self-increase 1 and then use the variable
$a--; $a = $a-1 use variable and then subtract 1 from the first
--$a; $a = $a-1 first from minus 1 and then with variable
Code:
$a = 10;
$b = $a + +; b=10,a=11
$c =--$b; C=9,b=9
$d = $c + + + + + + + $c; d=20,c=11
$e = $d-----$d; E=2,d=18
Two: String operators (.)

Three: assignment operator (= = = = *=%=. =)

Example:
Code:
$a = 10;
$a +=10; $a = $a +10;
$a-=10; $a = $a-10;
$a *=10; $a = $a *10;
$a/=10; $a = $a/10;
$a%=10; $a = $a% 10;
$a. = "ABC"; $a = $a. " ABC ";
Four: Comparison operators (> < >= <= = = = =!= or <>!==)//Also called conditional operators, relational operators
After comparison there is only one result: Boolean true False

= = = = = = = = = = =/= =

Example:
Code:
$a = 10;
if ($a =100) {
echo "correct";
}else{
echo "Error";
//The result is correct, but 10 is not greater than 100 because = is an assignment, not a comparison symbol

Code:
$a = 100;
if ($a ==100) {
echo "correct";
}else{
echo "Error";
//The result is correct, because = = = meaning is equal to or not.

Code:
$a = 100;
if ($a = = "100") {
echo "correct";
}else{
echo "Error";
//result is correct, because = = compare content, do not require type

Code:
$a = 100;
if ($a = = "100") {
echo "correct";
}else{
echo "Error";
//The result is an error because = = = Not only compares content, but also requires type, "100" is a character type

Code:
$a = 100;
if ($a ===100) {
echo "correct";
}else{
echo "Error";
}//Results are correct

!==//This is the requirement that the content is not the same and the type is different

Five: Logical operators (&& OR and | | OR OR! or not)

Logical operators can only manipulate bool values, and return a bool type

  Example:
Code:
   Var_dump (True && true); //true
   var_dump (True & & false); //false
   var_dump (true | | false); //true
   var_dump (!true); nbsp False
   Var_dump (!false); //true
 
  SIX: Bitwise operators (& | ^ ~ << >> >> ;>)
 & | can be used as both a logical operation symbol and a bitwise operational symbol
  short-circuit problem:&& and | | A short-circuit
 && when doing an operation, If the previous argument is false, then it is true, and the entire expression is false, so the following operand is not executed
 | | If the previous argument is true if the preceding parameter is false, the entire expression is true. So I'm not going to do the following operand
 & or | When doing an operation, both sides will be executed
  seven: Other operators (?: "@ =>->:: & $)
 
condition? Set up execution Here: Do not set up the execution here

  Example:
   code:
  $a =10
  $b = $a >5? $a:5; //If $a is greater than 5, assign $a to $b, or you will assign a value of 5 to $b< br>  echo $b; //result is a
 
  '//Execute system command
  Example: Www.111cn.net
  Code:
$ip = ' IP Config ';
echo "<pre>";
Echo $ip;
echo "</pre>";
  @ //Masking error
 
Example:
  code:
  @getType ();
 echo "Mkmkmkmkmkmk<br> ;";