PHP Operators

I. PHP Operators

An operator takes one or more expressions and results in a value.

• Arithmetic operators + - * / % **
• Assignment operators = += -= *= /= %= **=
• Comparison operators
• Conditional operators ?: ??
• Increment / Decrement ++ --
• Logical operators && || ! and or xor
• String operators . .=
• Array operators

Note; You can check Operator Precedence here.

II. Arithmetic operators

Arithmetic operators can perform mathematical operations + - * / % **:

• Addition.
• Subtraction.
• Multiplication.
• Division.
• Modulus.
• Exponentiation.

$x = 8;
$y = 2;

var_dump($x + $y); // int(10)
var_dump($x - $y); // int(6)
var_dump($x * $y); // int(16)
var_dump($x / $y); // int(4)
var_dump($x % $y); // int(0)
var_dump($x ** $y); // int(64)

Tips

• If we add + or - before a string, the value will be converted into an integer.

$x = +"8";
$y = - "2";

var_dump($x); // int(8)
var_dump($y); // int(-2)

• The type of division result is float unless both operands are integers and are evenly divisible.

$x = 10;
$y = 3;

var_dump($x / $y); // float(3.3333333333)

• If we want to get an infinity result when dividing 0, we use the fdiv() function.

$x = 7;
$y = 0;

var_dump(fdiv($x, $y)); // float(INF)

• Operands of modulo are converted to int before processing.

$x = 8.5;
$y = 3.2;

var_dump($x % $y); // int(2)

III. Assignment operators

The PHP assignment operators write a value to a variable. They include = += -= *= /= %= **=.

$x = 8;
$x += 2;

echo $x; // 10

IV. Comparison operators

We can use comparison operators to compare two values (number or string):

$x = 8;
$y = 2;

var_dump($x == $y);
var_dump($x === $y);
var_dump($x != $y);
var_dump($x !== $y);
var_dump($x <=> $y);

V. Conditional assignment operators

We can use conditional operators to set a value depending on conditions.

The ternary operator returns b if a is true, c if a is false.

$x = 26;
$result = $x >= 18 ? "allow": "not allow";
echo $result; // allow

Null coalescing is mainly used when working with null. It returns b if a is null.

$x = null;
$y = $x ?? "Hello";
echo $y; // Hello

VI. Increment / Decrement operators

We can use increment and decrement operators to increase or decrease a variable’s value.

$x = 10;

echo $x++; // 10
echo $x; // 11

echo ++$x; // 12;
echo --$x; // 11;

VII. Logical operators

We can use logical operators to combine conditional statements.

$x = true;
$y = false;
var_dump($x && $y); // bool(false)
var_dump($x || $y); // bool(true)
var_dump(!$x); // bool(false)

VIII. String operators

We can use string operators . .= for concatenation.

$x = "Hello";
$x .= "World";

echo $x; // HelloWorld

IX. Array operators

$x = ["a" => 1, "b" => 2];
$y = ["d" => 3, "e" => 4, "f" => 5];

echo "<pre>";
print_r($x+$y);
echo "</pre>";
/*
Array
(
    [a] => 1
    [b] => 2
    [d] => 3
    [e] => 4
    [f] => 5
)
*/