Unit 01

PHP Data Types

A data type specifies the type of value stored in a variable. PHP is loosely typed, so we do not need to explicitly declare the data type of a variable; PHP determines it automatically.

PHP supports 8 main data types.

For example, integers represent whole numbers, while floating-point numbers represent real or decimal numbers.

PHP Operators

Operators are symbols used to perform operations on variables and values. The important types of PHP operators are:

An array in PHP is used to store multiple values in a single variable. PHP supports different types of arrays and provides built-in functions for sorting and managing array data.

Types of Arrays in PHP

There are three main types of arrays:

<?php
$names = array("Fabio", "Klevi", "John");

echo $names[0];
?>
Output: Fabio

<?php
$namesAge = array(
    "Fabio" => "20",
    "Klevi" => "16",
    "John" => "43"
);

echo $namesAge["Fabio"];
?>
Output: 20

<?php
$socialNetworks = array(
    array("Facebook", "Feb", 21),
    array("Twitter", "Dec", 2),
    array("Instagram", "Aug", 15)
);
?>

Common Array Functions

PHP provides several built-in functions for working with arrays.

PHP tags are used to indicate where PHP code starts and ends in a file. The opening tag tells the server that the code following it is PHP code.

PHP provides the following types of tags:

<?php
echo "Hello";
?>

<?= "Hello"; ?>

<?
echo "Hello";
?>

<script language="php">
echo "Hello";
</script>

PHP provides the Filter Extension to validate and sanitize data. It helps developers handle user input safely without writing complex regular expressions.

Filtering is mainly used for two purposes: validation checks whether data is in the required format, and sanitization removes or converts unwanted or unsafe characters from data.

1. filter_var() Function

The filter_var() function is used to filter a specific variable.

Syntax: filter_var($variable, $filter, $options);

<?php
$email = "abc@gmail.com";

if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
    echo "Valid Email";
} else {
    echo "Invalid Email";
}
?>

Here, FILTER_VALIDATE_EMAIL checks whether the given value has a valid email format.

2. filter_input() Function

The filter_input() function directly gets data from superglobals such as $_GET and $_POST and filters it.

Syntax: filter_input($type, $variable_name, $filter);

For example: $age = filter_input(INPUT_POST, "age", FILTER_VALIDATE_INT);

Common Validation Filters

Common Sanitization Filters

Validation in PHP is the process of checking whether user input meets the expected format, type, or rules before it is processed or stored. It helps maintain data accuracy, integrity, and application security.

For example, validation can check whether an email address is properly formatted, whether a name has the correct length, whether a number is within a specified range, or whether a required field is empty.

Types of Input Validation

Validation Using PHP Filters

PHP provides built-in validation filters such as FILTER_VALIDATE_EMAIL, FILTER_VALIDATE_INT, and FILTER_VALIDATE_URL.

<?php
$email = "abc@gmail.com";

if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
    echo "Valid Email";
} else {
    echo "Invalid Email";
}
?>