Roudi Bronkhorst Basics of PHP

5. Operators and Expressions.

Different types of Operators in PHP:

In PHP, operators are symbols that perform operations on operands. Here’s a list of different types of operators in PHP along with their definitions:

Arithmetic Operators:

  • Arithmetic operators perform mathematical operations such as addition, subtraction, multiplication, division, modulus, and exponentiation.
<?php
$a = 10;
$b = 5;

// Addition
$sum = $a + $b;
echo "Sum: " . $sum . "<br>"; // Output: Sum: 15

// Subtraction
$difference = $a - $b;
echo "Difference: " . $difference . "<br>"; // Output: Difference: 5

// Multiplication
$product = $a * $b;
echo "Product: " . $product . "<br>"; // Output: Product: 50

// Division
$quotient = $a / $b;
echo "Quotient: " . $quotient . "<br>"; // Output: Quotient: 2

// Modulus
$remainder = $a % $b;
echo "Remainder: " . $remainder . "<br>"; // Output: Remainder: 0

// Exponentiation
$power = $a ** $b;
echo "Power: " . $power . "<br>"; // Output: Power: 100000
?>

Comparison Operators:

  • Comparison operators compare two values and return a boolean result (true or false) based on the comparison.
<?php
$a = 10;
$b = 5;

// Equal to (==)
$result1 = ($a == $b); // false

// Not equal to (!=)
$result2 = ($a != $b); // true

// Identical to (===)
$result3 = ($a === $b); // false

// Not identical to (!==)
$result4 = ($a !== $b); // true

// Greater than (>)
$result5 = ($a > $b); // true

// Less than (<)
$result6 = ($a < $b); // false

// Greater than or equal to (>=)
$result7 = ($a >= $b); // true

// Less than or equal to (<=)
$result8 = ($a <= $b); // false

// Output results
echo "Equal to (==): " . ($result1 ? 'true' : 'false') . "<br>";
echo "Not equal to (!=): " . ($result2 ? 'true' : 'false') . "<br>";
echo "Identical to (===): " . ($result3 ? 'true' : 'false') . "<br>";
echo "Not identical to (!==): " . ($result4 ? 'true' : 'false') . "<br>";
echo "Greater than (>): " . ($result5 ? 'true' : 'false') . "<br>";
echo "Less than (<): " . ($result6 ? 'true' : 'false') . "<br>";
echo "Greater than or equal to (>=): " . ($result7 ? 'true' : 'false') . "<br>";
echo "Less than or equal to (<=): " . ($result8 ? 'true' : 'false') . "<br>";
?>

Logical Operators:

  • Logical operators perform logical operations on boolean values and return a boolean result. They include && (logical AND), || (logical OR), and ! (logical NOT).
<?php
$a = true;
$b = false;

// Logical AND (&&)
$result1 = ($a && $b); // false

// Logical OR (||)
$result2 = ($a || $b); // true

// Logical NOT (!)
$result3 = !$a; // false
$result4 = !$b; // true

// Output results
echo "Logical AND (&&): " . ($result1 ? 'true' : 'false') . "<br>";
echo "Logical OR (||): " . ($result2 ? 'true' : 'false') . "<br>";
echo "Logical NOT (!) for \$a: " . ($result3 ? 'true' : 'false') . "<br>";
echo "Logical NOT (!) for \$b: " . ($result4 ? 'true' : 'false') . "<br>";
?>

String Operators:

  • String operators are used to concatenate strings. The concatenation operator (.) is used to combine two string values into one.
<?php
$string1 = "Hello";
$string2 = "World";

// Concatenation (.)
$result1 = $string1 . $string2; // HelloWorld

// Concatenation Assignment (.=)
$result2 = $string1;
$result2 .= $string2; // HelloWorld

// Output results
echo "Concatenation (.): " . $result1 . "<br>";
echo "Concatenation Assignment (.=): " . $result2 . "<br>";
?>

Increment/Decrement Operators:

  • Increment (++) and decrement (--) operators are used to increase or decrease the value of a variable by one.
<?php
$a = 5;

// Increment (++)
$result1 = ++$a; // Pre-increment: increments $a and returns the new value
$result2 = $a++; // Post-increment: returns the current value of $a and then increments it

// Decrement (--)
$result3 = --$a; // Pre-decrement: decrements $a and returns the new value
$result4 = $a--; // Post-decrement: returns the current value of $a and then decrements it

// Output results
echo "Pre-increment (++): " . $result1 . "<br>"; // Output: Pre-increment (++): 6
echo "Post-increment (++): " . $result2 . "<br>"; // Output: Post-increment (++): 6
echo "Pre-decrement (--): " . $result3 . "<br>"; // Output: Pre-decrement (--): 5
echo "Post-decrement (--): " . $result4 . "<br>"; // Output: Post-decrement (--): 5
?>

Ternary Operator:

  • The ternary operator (?:) is a shorthand version of the if-else statement. It evaluates a condition and returns one of two values based on the result of the condition.
<?php
$a = 10;
$b = 5;

// Ternary Operator (?:)
$result1 = ($a > $b) ? "Greater" : "Less or Equal"; // If $a is greater than $b, return "Greater", otherwise return "Less or Equal"
$result2 = ($a == $b) ? "Equal" : "Not Equal"; // If $a is equal to $b, return "Equal", otherwise return "Not Equal"

// Output results
echo "Result 1: " . $result1 . "<br>"; // Output: Result 1: Greater
echo "Result 2: " . $result2 . "<br>"; // Output: Result 2: Not Equal
?>

Null Coalescing Operator:

  • The null coalescing operator (??) is used to check if a variable is set and not null. It returns the value of the variable if it is set and not null, otherwise it returns a default value.
<?php
// Define variables with and without values
$var1 = null;
$var2 = "Hello";

// Null Coalescing Operator (??)
$result1 = $var1 ?? "Default Value"; // If $var1 is null, return "Default Value", otherwise return $var1
$result2 = $var2 ?? "Default Value"; // If $var2 is not null, return $var2, otherwise return "Default Value"

// Output results
echo "Result 1: " . $result1 . "<br>"; // Output: Result 1: Default Value
echo "Result 2: " . $result2 . "<br>"; // Output: Result 2: Hello
?>

Array Operators:

  • Array operators are used to manipulate arrays. The most common array operator is the union operator (+), which combines two arrays.
<?php
// Define two arrays
$array1 = array("a" => "apple", "b" => "banana");
$array2 = array("b" => "blueberry", "c" => "cherry");

// Array Union Operator (+)
$result = $array1 + $array2; // Merges $array1 and $array2, giving priority to the keys in $array1 if duplicates exist

// Output result
echo "Merged Array: <br>";
print_r($result);
?>

In this example:

  • $array1 contains elements with keys “a” and “b”.
  • $array2 contains elements with keys “b” and “c”.
  • The union operator + merges these two arrays, giving priority to the keys in $array1 if duplicates exist.
  • The output will contain elements from both arrays, but if a key exists in both arrays, the value from $array1 will be retained.

Type Operators:

  • Type operators are used to check the type of a variable. The instanceof operator is used to check if an object is an instance of a specific class.
<?php
// Define a class
class MyClass {
    public $prop;
}

// Instantiate an object of MyClass
$obj = new MyClass();

// Check if $obj is an instance of MyClass
$result1 = $obj instanceof MyClass; // true

// Check if $obj is an instance of stdClass
$result2 = $obj instanceof stdClass; // false

// Output results
echo "Result 1: " . ($result1 ? 'true' : 'false') . "<br>"; // Output: Result 1: true
echo "Result 2: " . ($result2 ? 'true' : 'false') . "<br>"; // Output: Result 2: false
?>

In this example:

  • We define a class MyClass with a public property $prop.
  • We instantiate an object $obj of the MyClass.
  • We use the instanceof operator to check if $obj is an instance of MyClass (which it is) and if it is an instance of stdClass (which it is not).
  • The output confirms the results of these checks.

These are the main types of operators in PHP. Each type serves a specific purpose and is used to perform different operations on operands. Understanding how to use these operators is essential for writing effective and efficient PHP code.

Different types of Expressions in PHP:

In programming, an expression is a combination of variables, operators, and/or function calls that produces a value. Here are the different types of expressions commonly used in PHP:

  1. Arithmetic Expressions:
    • Arithmetic expressions consist of arithmetic operators applied to numeric values, producing a numeric result.
    • Example: $result = $a + $b;
  2. String Expressions:
    • String expressions consist of string concatenation operators applied to string values, producing a string result.
    • Example: $fullName = $firstName . ' ' . $lastName;
  3. Boolean Expressions:
    • Boolean expressions consist of logical operators applied to boolean values, producing a boolean result.
    • Example: $result = ($a && $b);
  4. Comparison Expressions:
    • Comparison expressions consist of comparison operators applied to values, producing a boolean result.
    • Example: $result = ($a == $b);
  5. Assignment Expressions:
    • Assignment expressions consist of assignment operators applied to variables, assigning a value to the variable and producing the assigned value.
    • Example: $x += 5;
  6. Ternary Expressions:
    • Ternary expressions consist of a conditional expression (? :) used to evaluate a condition and return one of two values based on the result of the condition.
    • Example: $result = ($condition) ? $value1 : $value2;
  7. Function Call Expressions:
    • Function call expressions consist of function names followed by arguments enclosed in parentheses, producing the return value of the function.
    • Example: $result = myFunction($arg1, $arg2);
  8. Array Expressions:
    • Array expressions consist of array creation syntax, producing an array value.
    • Example: $myArray = array(1, 2, 3);
  9. Object Expressions:
    • Object expressions consist of object creation syntax, producing an object value.
    • Example: $myObject = new MyClass();
  10. Null Coalescing Expressions:
    • Null coalescing expressions consist of the null coalescing operator (??) used to check if a variable is set and not null, producing a value based on the variable’s state.
    • Example: $result = $variable ?? 'default';

These are the main types of expressions in PHP. Each type serves a specific purpose and is used to produce different types of values based on the operations performed. Understanding how to use these expressions is essential for writing effective and efficient PHP code.