Lecture Notes 3: Operators in PHP

 

Operations in PHP

1. Arithmetic Operations

Arithmetic operations are used to perform mathematical calculations on variables.

Basic Arithmetic Operators

Addition (+): Adds two numbers.

$a = 10;

$b = 20;

$result = $a + $b;  // Result: 30

Subtraction (-): Subtracts one number from another.

$result = $b - $a;  // Result: 10

Multiplication (*): Multiplies two numbers.

$result = $a * $b;  // Result: 200

Division (/): Divides one number by another.

$result = $b / $a;  // Result: 2

Modulus (%): Returns the remainder of the division of one number by another.

$result = $b % $a;  // Result: 0 (since 20 divided by 10 leaves no remainder)

Exponentiation (**): Raises one number to the power of another.

$result = $a ** 2;  // Result: 100 (10 raised to the power of 2)

Example:

 Arithmetic Operations

<?php     $x = 15;     $y = 4;          echo "Addition: " . ($x + $y);         // Output: 19     echo " Subtraction: " . ($x - $y);     // Output: 11     echo " Multiplication: " . ($x * $y);  // Output: 60     echo " Division: " . ($x / $y);        // Output: 3.75     echo " Modulus: " . ($x % $y);         // Output: 3 ?>

Output:

2. Assignment Operations

Assignment operations assign values to variables.

Basic Assignment Operators

Assignment (=): 

Assigns the value on the right to the variable on the left.

$x = 10;  // $x now holds the value 10

Compound Assignment Operators

Addition Assignment (+=): 

Adds the value on the right to the current value of the variable and assigns the result to the variable.

$x += 5;  // $x = $x + 5; 

Result: 15

Subtraction Assignment (-=): 

Subtracts the value on the right from the current value of the variable and assigns the result to the variable.

$x -= 3;  // $x = $x - 3;

Result: 7

Multiplication Assignment (*=): 

Multiplies the variable by the value on the right and assigns the result to the variable.

$x *= 2;  // $x = $x * 2; 

Result: 20

Division Assignment (/=): Divides the variable by the value on the right and assigns the result to the variable.

$x /= 5;  // $x = $x / 5; 

Result: 2

Modulus Assignment (%=): 

Takes the modulus of the variable by the value on the right and assigns the result to the variable.

$x %= 3;  // $x = $x % 3; 

Result: 1

Example: Assignment Operations

<?php     $x = 10;     $x += 5;   // Now $x is 15     echo "New Value: " . $x; ?>

Output:

3. Comparison Operations

Comparison operations compare two variables and return either true or false.

Comparison Operators

Equal (==): 

Checks if two values are equal.

$x == $y;

Identical (===): 

Checks if two values are equal and of the same type.

$x === $y;

Not Equal (!= or <>): 

Checks if two values are not equal.

$x != $y;

Not Identical (!==): 

Checks if two values are not equal or not of the same type.

$x !== $y;

Greater Than (>): 

Checks if the value on the left is greater than the value on the right.

$x > $y;

Less Than (<): 

Checks if the value on the left is less than the value on the right.

$x < $y;

Greater Than or Equal To (>=): 

Checks if the value on the left is greater than or equal to the value on the right.

$x >= $y;

Less Than or Equal To (<=): 

Checks if the value on the left is less than or equal to the value on the right.

$x <= $y;

Example: 

Comparison Operations

<?php     $a = 5;     $b = 10;          var_dump($a == $b);   // Output: bool(false)     var_dump($a != $b);   // Output: bool(true)     var_dump($a < $b);    // Output: bool(true) ?>

Output:

4. Logical Operations

Logical operations are used to combine comparison operations and control program flow.

Logical Operators

AND (&&): 

Returns true if both conditions are true.

$x && $y;

OR (||): 

Returns true if at least one of the conditions is true.

$x || $y;

NOT (!): 

Reverses the value of a condition. If true, returns false; if false, returns true.

!$x;

Example: Logical Operations

<?php     $a = 5;     $b = 10;          if ($a < $b && $b > 0) {         echo "Both conditions are true";     } ?>

Output:

5. Increment/Decrement Operations

These operations are used to increase or decrease the value of a variable by 1.

Increment Operators

Post-increment ($x++): 

Increases the variable's value by 1 after the operation.

$x++;

Pre-increment (++$x): 

Increases the variable's value by 1 before the operation.

++$x;

Decrement Operators

Post-decrement ($x--):

 Decreases the variable's value by 1 after the operation.

$x--;

Pre-decrement (--$x):

 Decreases the variable's value by 1 before the operation.

--$x;

Example: 

Increment/Decrement Operations

<?<?php     $x = 10;     echo $x++;   // Output: 10 (then $x becomes 11)     echo ++$x;   // Output: 12 ?>

Output:

6. String Operations

String operations allow you to manipulate and work with strings in PHP.

Concatenation (.)

Concatenates (joins) two strings together.

$first_name = "John";

$last_name = "Doe";

$full_name = $first_name . " " . $last_name;  // Result: "John Doe"

Concatenation Assignment (.=)

Appends the right-hand string to the left-hand string and assigns the result to the left-hand variable.

$text = "Hello";

$text .= " World";  // Result: "Hello World"

Example: String Operations

<?php     $greeting = "Hello";     $greeting .= ", World!";  // Append to string     echo $greeting;  // Output: Hello, World! ?>

Output:

Conclusion

By understanding and practicing these variable operations in PHP, you will gain the ability to manipulate data effectively in your PHP scripts.