PHP
What is PHP ?
- PHP is a server side scripting language.
- PHP full name is PHP Hypertext Preprocessor
- Php files have extention is .php
- Php can generate dynamic page content
- Php can create, open, read, write, delete, and close files on the server
- Php can collect form data
- Php can send and receive cookies
- Php can add, delete, modify data in your database
- Php runs on various platforms like Windows, Linux, Unix, Mac OS X, etc.
- Php is compatible with almost all servers used today like Apache, IIS, etc.
- Php 7 is much faster than the previous popular stable release (PHP 5.6)
PHP Syntax
A Php script can be placed anywhere in the document.
A Php script starts with
<?php and ends with ?>:<?php
// PHP code goes here
?>
Example
<html>
<body>
<?php
echo "Hello World!";
?>
</body>
</html>
Php statements end with a semicolon (
;).Comments :-
<html>
<body>
<?php
// This is a single-line comment
# This is also a single-line comment
/*
This is a multiple-lines comment block
that spans over multiple
lines
*/
?>
</body>
</html>
PHP Case Sensitivity
In Php, NO keywords (e.g.
if, else, while, echo, etc.), classes, functions, and user-defined functions are case-sensitive.<html>
<body>
<?php
ECHO "Manu Dhaker<br>";
echo "Manu Dhaker<br>";
EcHo "Manu Dhaker<br>";
?>
</body>
</html>
But variables names are case sensetive.
<html>
<body>
<?php
$name = "manu dhaker";
echo "My name is " . $name . "<br>";
echo "My name is " . $NAME . "<br>";
?>
</body>
</html>
PHP Variables
<?php
$name = "Manu Dhaker";
$char = 'M';
$a = 5;
$b = 10.5;
?>
PHP Variables
A variable can have a short name (like x and y) or a more descriptive name (age, carname, total_volume).
Rules for PHP variables:
- A variable starts with the
$sign, followed by the name of the variable - A variable name must start with a letter or the underscore character
- A variable name cannot start with a number
- A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
- Variable names are case-sensitive (
$nameand$NAMEare two different variables)
<html>
<body>
<?php
$name = "Manu Dhaker";
echo "I love $name!";
?>
</body>
</html>
2)==>><html>
<body>
<?php
$a = 5;
$b = 4;
echo $a + $b;
?>
</body>
</html>
PHP is a Loosely Typed Language
PHP Variables Scope
- local
- global
- static
Global and Local Scope
A variable declared outside a function has a GLOBAL SCOPE and can only be accessed outside a function...............................
<?php
$a = 5; // global scope
function myTest() {
// using a inside this function will generate an error echo "<p>Variable a inside function is: $x</p>";
}
myTest();
echo "<p>Variable a outside function is: $a</p>";
?>
$a = 5; // global scope
function myTest() {
// using a inside this function will generate an error echo "<p>Variable a inside function is: $x</p>";
}
myTest();
echo "<p>Variable a outside function is: $a</p>";
?>
PHP global
<?php
$a = 5;
$b = 10;
function myFunc() {
global $a, $b;
$b = $a + $b;
}
myFunc();
echo $b; // outputs 15?>
PHP static
<?php
function myFunc() {
static $a = 0;
echo $a;
$a++;
}
myFunc();
myFunc();
myFunc();
?>
function myFunc() {
static $a = 0;
echo $a;
$a++;
}
myFunc();
myFunc();
myFunc();
?>
PHP echo and print Statements
echoandprintare more or less the same.- They are both used to output data to the screen.
- The differences are small:
echohas no return value whileprinthas a return value of 1 so it can be used in expressions. echocan take multiple parameters (although such usage is rare) whileprintcan take one argument.echois marginally faster thanprint.
<?php
echo "<h2>PHP!</h2>";
echo "This ", "string ", "was ", "made ", "with multiple parameters.";
?>
<?php
print "<h2>PHP</h2>";
print "I'm learning PHP!";
?>
PHP Data Types
- String
- Integer
- Float (also called double)
- Boolean
- Array
- Object
- NULL
- Resource
PHP String
A string is a sequence of characters, like "Manu Dhaker".......................
<?php
$a = "Manu";
$b = 'Manu';
echo $a;
echo "<br>";
echo $b;
?>
PHP Integer
An integer data type is a non-decimal.
The PHP var_dump() function returns the data type and value................
<?php
$a = 5;
var_dump($a);
?>
$a = 5;
var_dump($a);
?>
PHP Float
A float data type is a number with a decimal point
<?php
$a = 4.789;
var_dump($a);
?>
PHP Boolean
<?php
$a = true;
$b = false;
var_dump($a);
var_dump($b);
?>
PHP Array
An array stores multiple values in one single variable.
<?php
$names = array("manu","kanu","trshu","drshu");
var_dump($names);
?>
PHP String Functions
- strlen()
- str_word_count()
- strrev()
- strpos()
- str_replace()
<?php
echo strlen("Hello manu!"); // outputs 11?>
<?php
echo str_word_count("Hello manu!"); // outputs 2?>
<?php
echo strrev("Hello manu!"); // outputs !unam olleH?>
<?phpecho strlen("Hello manu!"); // outputs 11?>
echo str_word_count("Hello manu!"); // outputs 2?>
echo strrev("Hello manu!"); // outputs !unam olleH?>
echo strpos("Hello manu!", "world"); // outputs 6?>
<?php
echo str_replace("world", "Manu", "Hello world!"); // outputs Hello Dolly!?>
PHP Constants
Constants are like variables except that once they are defined they cannot be changed or undefined.
define(name, value)
<?php
define("NAME", "Manu Dhaker!");
echo NAME;
?>
<?php
define("NAME", "Manu Dhaker!", true);
echo name;
?>
PHP Constant Arrays
In PHP7, you can create an Array constant using the
define() function.<?php
define("name", [
"jenny",
"dolly",
"payal"
]);
echo name[0];
?>
Constants are automatically global and can be used across the entire script.
PHP Operators
- Arithmetic operators
- Assignment operators
- Comparison operators
- Increment/Decrement operators
- Logical operators
- String operators
- Array operators
- Conditional assignment operators
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