Author: saqibkhan

PHP recognizes the three dots symbol (…) as the spread operator. The spread operator is also sometimes called the splat operator. This operator was first introduced in PHP version 7.4. It can be effectively used in many cases such as unpacking arrays.

Example 1

In the example below, the elements in $arr1 are inserted in $arr2 after a list of its own elements.

Open Compiler

<?php
   $arr1 = [4,5];
   $arr2 = [1,2,3, ...$arr1];

   print_r($arr2);
?>

It will produce the following output −

Array
(
   [0] => 1
   [1] => 2
   [2] => 3
   [3] => 4
   [4] => 5
)

Example 2

The Spread operator can be used more than once in an expression. For example, in the following code, a third array is created by expanding the elements of two arrays.

Open Compiler

<?php
   $arr1 = [1,2,3];
   $arr2 = [4,5,6];
   $arr3 = [...$arr1, ...$arr2];

   print_r($arr3);
?>

It will produce the following output −

Array
(
   [0] => 1
   [1] => 2
   [2] => 3
   [3] => 4
   [4] => 5
   [5] => 6
)

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Example 3

Note that the same result can be obtained with the use of array_merge() function, as shown below −

Open Compiler

<?php
   $arr1 = [1,2,3];
   $arr2 = [4,5,6];
   $arr3 = array_merge($arr1, $arr2);

   print_r($arr3);
?>

It will produce the same output −

Array
(
   [0] => 1
   [1] => 2
   [2] => 3
   [3] => 4
   [4] => 5
   [5] => 6
)

However, the use of (…) operator is much more efficient as it avoids the overhead a function call.

Example 4

PHP 8.1.0 also introduced another feature that allows using named arguments after unpacking the arguments. Instead of providing a value to each of the arguments individually, the values from an array will be unpacked into the corresponding arguments, using … (three dots) before the array.

Open Compiler

<?php  
   function  myfunction($x, $y, $z=30) {
  echo "x = $x  y = $y  z = $z";
   }

   myfunction(...[10, 20], z:30);
?>

It will produce the following output −

x = 10  y = 20  z = 30

Example 5

In the following example, the return value of a function is an array. The array elements are then spread and unpacked.

Open Compiler

<?php
   function get_squares() {
  for ($i = 0; $i &lt; 5; $i++) {
     $arr&#91;] = $i**2;
  }
  return $arr;
   }
   $squares = [...get_squares()];
   print_r($squares);
?>

It will produce the following output −

Array
(
   [0] => 0
   [1] => 1
   [2] => 4
   [3] => 9
   [4] => 16
)

You would use conditional operators in PHP when there is a need to set a value depending on conditions. It is also known as ternary operator. It first evaluates an expression for a true or false value and then executes one of the two given statements depending upon the result of the evaluation.

Ternary operators offer a concise way to write conditional expressions. They consist of three parts: the condition, the value to be returned if the condition evaluates to true, and the value to be returned if the condition evaluates to false.

Syntax

The syntax is as follows −

condition ? value_if_true : value_if_false

Ternary operators are especially useful for shortening if-else statements into a single line. You can use a ternary operator to assign different values to a variable based on a condition without needing multiple lines of code. It can improve the readability of the code.

However, you should use ternary operators judiciously, else you will end up making the code too complex for others to understand.

Example

Try the following example to understand how the conditional operator works in PHP. Copy and paste the following PHP program in test.php file and keep it in your PHP Server’s document root and browse it using any browser.

Open Compiler

<?php
   $a = 10;
   $b = 20;

   /* If condition is true then assign a to result otheriwse b */
   $result = ($a > $b ) ? $a :$b;

   echo "TEST1 : Value of result is $result \n";

   /* If condition is true then assign a to result otheriwse b */
   $result = ($a < $b ) ? $a :$b;

   echo "TEST2 : Value of result is $result";
?>

It will produce the following output −

TEST1 : Value of result is 20
TEST2 : Value of result is 10

PHP defines the following set of symbols to be used as operators on array data types −

The Union operator appends the right-hand array appended to left-hand array. If a key exists in both arrays, the elements from the left-hand array will be used, and the matching elements from the right-hand array will be ignored.

Example: Union Opeator in PHP

The following example shows how you can use the union operator in PHP −

Open Compiler

<?php
   $arr1=array("phy"=>70, "che"=>80, "math"=>90);
   $arr2=array("Eng"=>70, "Bio"=>80,"CompSci"=>90);
   $arr3=$arr1+$arr2;
   var_dump($arr3);
?>

It will produce the following output −

array(6) {
   ["phy"]=>
   int(70)
   ["che"]=>
   int(80)
   ["math"]=>
   int(90)
   ["Eng"]=>
   int(70)
   ["Bio"]=>
   int(80)
   ["CompSci"]=>
   int(90)
}

Example: When Two Array are Equal

Two arrays are said to be equal if they have the same key-value pairs.

In the following example, we have an indexed array and other associative array with keys corresponding to index of elements in first. Hence, both are equal.

Open Compiler

<?php
   $arr1=array(0=>70, 2=>80, 1=>90);
   $arr2=array(70,90,80);
   var_dump ($arr1==$arr2);
   var_dump ($arr2!=$arr1);
?>

It will produce the following output −

bool(true)
bool(false)

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Example: When Two Arrays are Identical

Arrays are identical if and only if both of them have same set of key-value pairs and in same order.

Open Compiler

<?php
   $arr1=array(0=>70, 1=>80, 2=>90);
   $arr2=array(70,90,80);
   var_dump ($arr1===$arr2);
   $arr3=[70,80,90];
   var_dump ($arr3===$arr1);
?>

It will produce the following output −

bool(false)
bool(true)

You can use assignment operators in PHP to assign values to variables. Assignment operators are shorthand notations to perform arithmetic or other operations while assigning a value to a variable. For instance, the “=” operator assigns the value on the right-hand side to the variable on the left-hand side.

Additionally, there are compound assignment operators like +=, -= , *=, /=, and %= which combine arithmetic operations with assignment. For example, “$x += 5” is a shorthand for “$x = $x + 5”, incrementing the value of $x by 5. Assignment operators offer a concise way to update variables based on their current values.

The following table highligts the assignment operators that are supported by PHP −

Example

The following example shows how you can use these assignment operators in PHP −

Open Compiler

<?php
   $a = 42;
   $b = 20;

   $c = $a + $b;
   echo "Addition Operation Result: $c \n";

   $c += $a;
   echo "Add AND Assignment Operation Result: $c \n";

   $c -= $a;
   echo "Subtract AND Assignment Operation Result: $c \n";

   $c *= $a;
   echo "Multiply AND Assignment Operation Result: $c \n";

   $c /= $a;
   echo "Division AND Assignment Operation Result: $c \n";

   $c %= $a;
   echo "Modulus AND Assignment Operation Result: $c";
?>

It will produce the following output −

Addition Operation Result: 62 
Add AND Assignment Operation Result: 104 
Subtract AND Assignment Operation Result: 62 
Multiply AND Assignment Operation Result: 2604 
Division AND Assignment Operation Result: 62 
Modulus AND Assignment Operation Result: 20

In PHP, logical operators are used to combine conditional statements. These operators allow you to create more complex conditions by combining multiple conditions together.

Logical operators are generally used in conditional statements such as if, while, and for loops to control the flow of program execution based on specific conditions.

The following table highligts the logical operators that are supported by PHP.

Assume variable $a holds 10 and variable $b holds 20, then −

Example

The following example shows how you can use these logical operators in PHP −

Open Compiler

<?php
   $a = 42;
   $b = 0;

   if ($a && $b) {
  echo "TEST1 : Both a and b are true \n";
   } else {
  echo "TEST1 : Either a or b is false \n";
   }

   if ($a and $b) {
  echo "TEST2 : Both a and b are true \n";
   } else {
  echo "TEST2 : Either a or b is false \n";
   }

   if ($a || $b) {
  echo "TEST3 : Either a or b is true \n";
   } else {
  echo "TEST3 : Both a and b are false \n";
   }

   if ($a or $b) {
  echo "TEST4 : Either a or b is true \n";
   } else {
  echo "TEST4 : Both a and b are false \n";
   }

   $a = 10;
   $b = 20;

   if ($a) {
  echo "TEST5 : a is true \n";
   } else {
  echo "TEST5 : a is false \n";
   }

   if ($b) {
  echo "TEST6 : b is true \n";
   } else {
  echo "TEST6 : b is false \n";
   }

   if (!$a) {
  echo "TEST7 : a is true \n";
   } else {
  echo "TEST7 : a is false \n";
   }

   if (!$b) {
  echo "TEST8 : b is true \n";
   } else {
  echo "TEST8 : b is false";
   }
?>

It will produce the following output −

TEST1 : Either a or b is false 
TEST2 : Either a or b is false 
TEST3 : Either a or b is true 
TEST4 : Either a or b is true 
TEST5 : a is true 
TEST6 : b is true 
TEST7 : a is false 
TEST8 : b is false

In PHP, Comparison operators are used to compare two values and determine their relationship. These operators return a Boolean value, either True or False, based on the result of the comparison.

The following table highligts the comparison operators that are supported by PHP. Assume variable $a holds 10 and variable $b holds 20, then −

Additionally, these operators can also be combined with logical operators (&&, ||, !) to form complex conditions for decision making in PHP programs.

Example

The following example shows how you can use these comparison operators in PHP −

Open Compiler

<?php
   $a = 42;
   $b = 20;

   if ($a == $b) {
  echo "TEST1 : a is equal to b \n";
   } else {
  echo "TEST1 : a is not equal to b \n";
   }

   if ($a > $b) {
  echo "TEST2 : a is greater than  b \n";
   } else {
  echo "TEST2 : a is not greater than b \n";
   }

   if ($a < $b) {
  echo "TEST3 : a is less than  b \n";
   } else {
  echo "TEST3 : a is not less than b \n";
   }

   if ($a != $b) {
  echo "TEST4 : a is not equal to b \n";
   } else {
  echo "TEST4 : a is equal to b \n";
   }

   if ($a >= $b) {
  echo "TEST5 : a is either greater than or equal to b \n";
   } else {
  echo "TEST5 : a is neither greater than nor equal to b \n";
   }    
   if ($a <= $b) {
  echo "TEST6 : a is either less than or equal to b \n";
   } else {
  echo "TEST6 : a is neither less than nor equal to b";
   }
?>

It will produce the following output −

TEST1 : a is not equal to b
TEST2 : a is greater than b
TEST3 : a is not less than b
TEST4 : a is not equal to b
TEST5 : a is either greater than or equal to b
TEST6 : a is neither less than nor equal to b

What are Operators in PHP?

As in any programming language, PHP also has operators which are symbols (sometimes keywords) that are predefined to perform certain commonly required operations on one or more operands.

For example, using the expression “4 + 5” is equal to 9. Here “4” and “5” are called operands and “+” is called an operator.

We have the following types of operators in PHP −

• Arithmetic Operators
• Comparison Operators
• Logical Operators
• Assignment Operators
• String Operators
• Array Operators
• Conditional (or Ternary Operators)

This chapter will provide an overview of how you can use these operators in PHP. In the subsequent chapters, we will take a closer look at each of the operators and how they work.

Arithmetic Operators in PHP

We use Arithmetic operators to perform mathematical operations like addition, subtraction, multiplication, division, etc. on the given operands. Arithmetic operators (excluding the increment and decrement operators) always work on two operands, however the type of these operands should be the same.

The following table highligts the arithmetic operators that are supported by PHP. Assume variable “$a” holds 42 and variable “$b” holds 20 −

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Comparison Operators in PHP

You would use Comparison operators to compare two operands and find the relationship between them. They return a Boolean value (either true or false) based on the outcome of the comparison.

The following table highligts the comparison operators that are supported by PHP. Assume variable $a holds 10 and variable $b holds 20, then −

Logical Operators in PHP

You can use Logical operators in PHP to perform logical operations on multiple expressions together. Logical operators always return Boolean values, either true or false.

Logical operators are commonly used with conditional statements and loops to return decisions according to the Boolean conditions. You can also combine them to manipulate Boolean values while dealing with complex expressions.

The following table highligts the logical operators that are supported by PHP.

Assume variable $a holds 10 and variable $b holds 20, then −

Assignment Operators in PHP

You can use Assignment operators in PHP to assign or update the values of a given variable with a new value. The right-hand side of the assignment operator holds the value and the left-hand side of the assignment operator is the variable to which the value will be assigned.

The data type of both the sides should be the same, else you will get an error. The associativity of assignment operators is from right to left. PHP supports two types of assignment operators −

• Simple Assignment Operator − It is the most commonly used operator. It is used to assign value to a variable or constant.
• Compound Assignment Operators − A combination of the assignment operator (=) with other operators like +, *, /, etc.

The following table highligts the assignment operators that are supported by PHP −

String Operators in PHP

There are two operators in PHP for working with string data types −

• The “.” (dot) operator is PHP’s concatenation operator. It joins two string operands (characters of right hand string appended to left hand string) and returns a new string.
• PHP also has the “.=” operator which can be termed as the concatenation assignment operator. It updates the string on its left by appending the characters of right hand operand.

$third=$first.$second;$leftstring.=$rightstring;

Array Operators in PHP

PHP defines the following set of symbols to be used as operators on array data types −

Conditional Operators in PHP

There is one more operator in PHP which is called conditional operator. It is also known as ternary operator. It first evaluates an expression for a true or false value and then executes one of the two given statements depending upon the result of the evaluation.

Operator Categories in PHP

All the operators we have discussed above can be categorised into following categories −

• Unary prefix operators, which precede a single operand.
• Binary operators, which take two operands and perform a variety of arithmetic and logical operations.
• The conditional operator (a ternary operator), which takes three operands and evaluates either the second or third expression, depending on the evaluation of the first expression.
• Assignment operators, which assign a value to a variable.

Operator Precedence in PHP

Precedence of operators decides the order of execution of operators in an expression. For example, in “2+6/3”, division of 6/3 is done first and then the addition of “2+2” takes place because the division operator “/” has higher precedence over the addition operator “+”.

To force a certain operator to be called before other, parentheses should be used. In this example, (2+6)/3 performs addition first, followed by division.

Some operators may have the same level of precedence. In that case, the order of associativity (either left or right) decides the order of operations. Operators of same precedence level but are non-associative cannot be used next to each other.

The following table lists the PHP operators in their decreasing order of precedence −