What Does This Symbol Mean in PHP <=

Reference — What does this symbol mean in PHP?

Incrementing / Decrementing Operators

++ increment operator

-- decrement operator

Example    Name              Effect
---------------------------------------------------------------------
++$a       Pre-increment     Increments $a by one, then returns $a.
$a++       Post-increment    Returns $a, then increments $a by one.
--$a       Pre-decrement     Decrements $a by one, then returns $a.
$a--       Post-decrement    Returns $a, then decrements $a by one.

These can go before or after the variable.

If put before the variable, the increment/decrement operation is done to the variable first then the result is returned. If put after the variable, the variable is first returned, then the increment/decrement operation is done.

For example:

$apples = 10;
for ($i = 0; $i < 10; ++$i) {
    echo 'I have ' . $apples-- . " apples. I just ate one.\n";
}

Live example

In the case above ++$i is used, since it is faster. $i++ would have the same results.

Pre-increment is a little bit faster because it really increments the variable and after that 'returns' the result. Post-increment creates a special variable, copies there the value of the first variable and only after the first variable is used, replaces its value with second's.

However, you must use $apples--, since first, you want to display the current number of apples, and then you want to subtract one from it.

You can also increment letters in PHP:

$i = "a";
while ($i < "c") {
    echo $i++;
}

Once z is reached aa is next, and so on.

Note that character variables can be incremented but not decremented and even so only plain ASCII characters (a-z and A-Z) are supported.

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Stack Overflow Posts:

• Understanding Incrementing

What does = mean in PHP?

=> is the separator for associative arrays. In the context of that foreach loop, it assigns the key of the array to $user and the value to $pass.

Example:

$user_list = array(
    'dave' => 'apassword',
    'steve' => 'secr3t'
);

foreach ($user_list as $user => $pass) {
    echo "{$user}'s pass is: {$pass}\n";
}
// Prints: 
// "dave's pass is: apassword"
// "steve's pass is: secr3t"

Note that this can be used for numerically indexed arrays too.

Example:

$foo = array('car', 'truck', 'van', 'bike', 'rickshaw');
foreach ($foo as $i => $type) {
    echo "{$i}: {$type}\n";
}
// prints:
// 0: car
// 1: truck
// 2: van
// 3: bike
// 4: rickshaw

What does @ mean in PHP?

The @ operator tells PHP to suppress error messages, so that they will not be shown.

For instance, using:

$result = mysql_query("this is an invalid query");

would result in a warning being shown, telling you that the MySQL query is invalid, while

$result = @mysql_query("this is still an invalid query");

would not.

Note, however, that this is very bad programming practice as it does not make error disappear, it just hides them, and it makes debugging a heck of a lot worse since you can't see what's actually wrong with your code.

Instead of using @, you should disable error_reporting and display_errors just display_errors in php.ini

What does ' ?=' mean in PHP?

It's a shorthand for <?php echo $a; ?>.

It's enabled by default since 5.4.0 regardless of php.ini settings.

What does this symbol mean in JavaScript?

See the documentation on MDN about expressions and operators and statements.

Basic keywords and general expressions

this keyword:

• How does the "this" keyword work?

var x = function() vs. function x()  —  Function declaration syntax

• var functionName = function() {} vs function functionName() {}

(function(){…})()  —  IIFE (Immediately Invoked Function Expression)

• What is the purpose?, How is it called?
• Why does (function(){…})(); work but function(){…}(); doesn't?
• (function(){…})(); vs (function(){…}());
• shorter alternatives:
  
  • !function(){…}(); - What does the exclamation mark do before the function?
  • +function(){…}(); - JavaScript plus sign in front of function expression
  • !function(){ }() vs (function(){ })(), ! vs leading semicolon
• (function(window, undefined){…}(window));

someFunction()()  —  Functions which return other functions

• Two sets of parentheses after function call

=>  —  Equal sign, greater than: arrow function expression syntax

• What's the meaning of "=>" (an arrow formed from equals & greater than) in JavaScript?

|>  —  Pipe, greater than: Pipeline operator

• What does the "|>" operator do in JavaScript?

function*, yield, yield*  —  Star after function or yield: generator functions

• What is "function*" in JavaScript?
• What's the yield keyword in JavaScript?
• Delegated yield (yield star, yield *) in generator functions

[], Array()  —  Square brackets: array notation

• What’s the difference between "Array()" and "[]" while declaring a JavaScript array?
• What is array literal notation in javascript and when should you use it?

If the square brackets appear on the left side of an assignment ([a] = ...), or inside a function's parameters, it's a destructuring assignment.

{key: value}  —  Curly brackets: object literal syntax (not to be confused with blocks)

• What do curly braces in JavaScript mean?
• Javascript object literal: what exactly is {a, b, c}?
• What do square brackets around a property name in an object literal mean?
• How does this object method definition work without the "function" keyword? (ES2015 Method definitions)

If the curly brackets appear on the left side of an assignment ({ a } = ...) or inside a function's parameters, it's a destructuring assignment.

`…${…}…`  —  Backticks, dollar sign with curly brackets: template literals

• What does this `…${…}…` code from the node docs mean?
• Usage of the backtick character (`) in JavaScript?
  
• What is the purpose of template literals (backticks) following a function in ES6?

/…/  —  Slashes: regular expression literals

• Meaning of javascript text between two slashes

$  —  Dollar sign in regex replace patterns: $$, $&, $`, $', $n

• JavaScript replace() method dollar signs

()  —  Parentheses: grouping operator

• MDN: Grouping operator

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Property-related expressions

obj.prop, obj[prop], obj["prop"]  —  Square brackets or dot: property accessors

• JavaScript property access: dot notation vs. brackets?

?., ?.[], ?.()  —  Question mark, dot: optional chaining operator

• Question mark after parameter
• Null-safe property access (and conditional assignment) in ES6/2015
• Optional Chaining in JavaScript
• Is there a null-coalescing (Elvis) operator or safe navigation operator in javascript?
• Is there a "null coalescing" operator in JavaScript?

::  —  Double colon: bind operator

• JavaScript double colon (bind operator)

new operator

• What is the 'new' keyword in JavaScript?
• What is "new.target"?

...iter  —  Three dots: spread syntax; rest parameters

• (...rest) => {}  —  What is the meaning of “…args” (three dots) in a function definition?
• fn(...args)  —  What is the meaning of “foo(…arg)” (three dots in a function call)?
• [...iter]  —  javascript es6 array feature […data, 0] “spread operator”
• {...props}  —  Javascript Property with three dots (…), What does the '…rest' stand for in this object destructuring?

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Increment and decrement

++, --  —  Double plus or minus: pre- / post-increment / -decrement operators

• ++someVariable vs someVariable++ in Javascript

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Unary and binary (arithmetic, logical, bitwise) operators

delete operator

• What is the purpose of the delete operator in Javascript?

void operator

• What does `void 0` mean?

+, -  —  Plus and minus: addition or concatenation, and subtraction operators; unary sign operators

• What does = +_ mean in JavaScript, Single plus operator in javascript
• What's the significant use of unary plus and minus operators?
• Why is [1,2] + [3,4] = "1,23,4" in JavaScript?
• Why does JavaScript handle the plus and minus operators between strings and numbers differently?

|, &, ^, ~  —  Single pipe, ampersand, circumflex, tilde: bitwise OR, AND, XOR, & NOT operators

• What do these JavaScript bitwise operators do?
• How to: The ~ operator?
• Is there a & logical operator in Javascript
• What does the "|" (single pipe) do in JavaScript?
• What does the operator |= do in JavaScript?
• What does the ^ (caret) symbol do in JavaScript?
• Using bitwise OR 0 to floor a number, How does x|0 floor the number in JavaScript?
• Why does ~1 equal -2?
• What does ~~ ("double tilde") do in Javascript?
• How does !!~ (not not tilde/bang bang tilde) alter the result of a 'contains/included' Array method call? (also here and here)

%  —  Percent sign: remainder operator

• What does % do in JavaScript?

&&, ||, !  —  Double ampersand, double pipe, exclamation point: logical operators

• Logical operators in JavaScript — how do you use them?
• Logical operator || in javascript, 0 stands for Boolean false?
• What does "var FOO = FOO || {}" (assign a variable or an empty object to that variable) mean in Javascript?, JavaScript OR (||) variable assignment explanation, What does the construct x = x || y mean?
• Javascript AND operator within assignment
• What is "x && foo()"? (also here and here)
• What is the !! (not not) operator in JavaScript?
• What is an exclamation point in JavaScript?

??  —  Double question mark: nullish-coalescing operator

• How is the nullish coalescing operator (??) different from the logical OR operator (||) in ECMAScript?
• Is there a null-coalescing (Elvis) operator or safe navigation operator in javascript?
• Is there a "null coalescing" operator in JavaScript?

**  —  Double star: power operator (exponentiation)

• x ** 2 is equivalent to Math.pow(x, 2)
• Is the double asterisk ** a valid JavaScript operator?
• MDN documentation

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Equality operators

==, ===  —  Equal signs: equality operators

• Which equals operator (== vs ===) should be used in JavaScript comparisons?
• How does JS type coercion work?
• In Javascript, <int-value> == "<int-value>" evaluates to true. Why is it so?
• [] == ![] evaluates to true
• Why does "undefined equals false" return false?
• Why does !new Boolean(false) equals false in JavaScript?
• Javascript 0 == '0'. Explain this example
• Why false == "false" is false?

!=, !==  —  Exclamation point and equal signs: inequality operators

• != vs. !==
• What is the difference between != and !== operators in JavaScript?

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Bit shift operators

<<, >>, >>>  —  Two or three angle brackets: bit shift operators

• What do these JavaScript bitwise operators do?
• Double more-than symbol in JavaScript
• What is the JavaScript >>> operator and how do you use it?

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Conditional operator

…?…:…  —  Question mark and colon: conditional (ternary) operator

• Question mark and colon in JavaScript
• Operator precedence with Javascript Ternary operator
• How do you use the ? : (conditional) operator in JavaScript?

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Assignment operators

=  —  Equal sign: assignment operator

• What is the difference between the `=` and `==` operators and what is `===`? (Single, double, and triple equals)

This symbol is also used for default parameters or default values in a destructuring assignment:

• what does (state = {}) => state means
• What does ({"key": "value"} = {}) syntax mean inside a JavaScript function

%=  —  Percent equals: remainder assignment

• Having Confusion with Modulo operator

+=  —  Plus equals: addition assignment operator

• How does += (plus equal) work?

&&=, ||=, ??=  —  Double ampersand, pipe, or question mark, followed by equal sign: logical assignments

• What purpose do &&=, ||= and ??= serve?
• Replace a value if null or undefined in JavaScript
• Set a variable if undefined
• Ruby’s ||= (or equals) in JavaScript?
• Original proposal
• Specification

<<=, >>=, >>>=, &=, ^=, |= — Double less than, double greater than, triple greater than, ampersand, caret, or pipe followed by equal sign: bitwise assignments

• What do these JavaScript bitwise operators do?

Destructuring

• of function parameters: Where can I get info on the object parameter syntax for JavaScript functions?
• of arrays: Multiple assignment in javascript? What does [a,b,c] = [1, 2, 3]; mean?
• of objects/imports: Javascript object bracket notation ({ Navigation } =) on left side of assign

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Comma operator

,  —  Comma operator (not to be confused with the comma used in variable declarations)

• What does a comma do in JavaScript expressions?
• Comma operator returns first value instead of second in argument list?
• When is the comma operator useful?

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Control flow

{…}  — Curly brackets: blocks (not to be confused with object literal syntax)

• JavaScript curly braces with no function or json

Declarations

var, let, const  —  Declaring variables

• What's the difference between using "let" and "var"?
• Are there constants in JavaScript?
• What is the temporal dead zone?
• var a, b;  —  Comma used in variable declarations (not to be confused with the comma operator): JavaScript variable definition: Commas vs. Semicolons

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Label

label:  —  Colon: labels

• What does the JavaScript syntax foo: mean?
• What does ':' (colon) do in JavaScript?

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Other

123n  —  n after integer: BigInt

• What does character 'n' after numeric literal mean in JavaScript?

#  —  Hash (number sign): Private methods or private fields

• What does the # symbol do in JavaScript?

_  —  Underscore: separator in numeric literals

• Javascript numeric separators?
• Is there a Javascript equivalent to the Ruby syntax using underscores (e.g. 10_000 = 10000) to make larger integers human readable?

!= PHP operator, how to write not equal to or greater than?

Isn't not greater than or equal to x the same as less than x ?

What is = (the 'Spaceship' Operator) in PHP 7?

The <=> ("Spaceship") operator will offer combined comparison in that it will :

Return 0 if values on either side are equal
Return 1 if the value on the left is greater
Return -1 if the value on the right is greater

The rules used by the combined comparison operator are the same as the currently used comparison operators by PHP viz. <, <=, ==, >= and >. Those who are from Perl or Ruby programming background may already be familiar with this new operator proposed for PHP7.

   //Comparing Integers

    echo 1 <=> 1; //output  0
    echo 3 <=> 4; //output -1
    echo 4 <=> 3; //output  1

    //String Comparison

    echo "x" <=> "x"; //output  0
    echo "x" <=> "y"; //output -1
    echo "y" <=> "x"; //output  1

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