| Introduction to Web Development |
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| Basic PHP Syntax |
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| PHP Basics |
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| Variables and Data Types |
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| Functions in PHP |
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| User-defined Functions |
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| Built-in Functions |
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| Variable Scope |
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| Include and Require |
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| Working with Forms |
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| Forms in HTML |
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| Form Handling in PHP |
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| Working with Files |
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| File Handling |
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| File System Functions |
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| Working with Databases |
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| Introduction to Databases |
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| Advanced PHP Techniques |
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| Object-Oriented Programming (OOP) |
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| Error and Exception Handling |
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1. String
A string is a sequence of characters enclosed in quotes. PHP supports both single-quoted and double-quoted strings.
- Single-quoted strings: These are treated almost literally. Variables and escape sequences (except for
\\and\') are not interpreted.
$name = 'John';
echo 'Hello, $name'; // Output: Hello, $name
- Double-quoted strings: These allow for variable interpolation and escape sequences.
$name = 'John';
echo "Hello, $name"; // Output: Hello, John
2. Integer
An integer is a whole number without a decimal point. It can be positive or negative.
- Decimal (base 10):
$int = 42;
- Hexadecimal (base 16):
$hex = 0x2A; // 42 in decimal
- Octal (base 8):
$octal = 052; // 42 in decimal
3. Float
A float (or double) is a number with a decimal point or a number in exponential form.
$float = 3.14;
$floatExp = 2.5e3; // 2500
4. Boolean
A boolean represents two possible states: ‘TRUE‘ or’FALSE‘.
$isTrue = true;
$isFalse = false;
5. Array
An array is a collection of values. In PHP, arrays are actually ordered maps, meaning they associate values to keys.
- Indexed arrays:
$array = array(1, 2, 3);
echo $array[0]; // Output: 1
- Associative arrays:
$assocArray = array("name" => "John", "age" => 30);
echo $assocArray["name"]; // Output: John
- Multidimensional arrays:
$multiArray = array(
array(1, 2, 3),
array(4, 5, 6),
array(7, 8, 9)
);
echo $multiArray[1][2]; // Output: 6
6. Object
An object is an instance of a class. Objects allow you to model real-world entities with properties and methods.
class Person {
public $name;
public $age;
function __construct($name, $age) {
$this->name = $name;
$this->age = $age;
}
function greet() {
return "Hello, my name is " . $this->name;
}
}
$person = new Person("John", 30);
echo $person->greet(); // Output: Hello, my name is John
7. NULL
NULL is a special type that only has one value: NULL. It represents a variable with no value.
$var = NULL;
if (is_null($var)) {
echo "The variable is NULL";
}
Type Juggling and Type Casting
PHP is a loosely typed language, which means it can automatically convert between different types based on the context (type juggling). However, you can also explicitly cast variables.
- Automatic type juggling:
$sum = "3" + 4; // $sum is 7 (integer)
- Explicit type casting:
$num = (int) "42"; // $num is 42 (integer)
$str = (string) 42; // $str is "42" (string)
Understanding these data types and their behaviors is essential for effective PHP programming. Each type comes with its own set of functions and methods that can be used to manipulate and handle data efficiently.
