Lecture Notes On Class 3
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.