PHP | NIKHIL'S BLOG

What is PHP ?

What is a PHP File?

PHP files can contain text, HTML, CSS, JavaScript, and PHP code.
PHP code are executed on the server, and the result is returned to the browser as plain HTML.
PHP files have extension ".php".

History of PHP :

PHP was created in 1994 by Rasmus Lerdorf. It was written in the C Programming Language.
It is the most widely used server side programming language used to power some of the largest websites online today.
It makes creating websites easier since we can use a template system like WordPress does and embed HTML which will help us output web pages.
In one file we can use HTML, CSS, JavaScript and PHP.
It also helps us connect to a database like MySQL which makes it very useful.
It is also one of the most well documented server side programming languages and we will find an endless amount of tutorials out there to learn how to use.

Features of PHP :

Pro's of PHP :

Con's of PHP :

Setup and installation :

Extract the files in the downloaded zip file and copy all the files into the php folder.

Open the php.ini file and give the extension directory path and remove the comments for cgi and fast cgi.

We can set default document i.e., if we didn't specify the file this file will get executed when we enter localhost.

Go to handler mappings and add the module mapping by giving the module name and executable file.

Add a website by giving the site name and choose the folder that php files exist.

Basic concepts in php :
Variable :

In PHP, a variable starts with the $ sign, followed by the name of the variable.
Rules for PHP variables :

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 ($age and $AGE are two different variables).

Data Types :

Variables can store data of different types, and different data types can do different things.
PHP supports the following data types :

Strings :

A PHP string is a sequence of characters i.e. used to store and manipulate text.
The strlen() function returns the length of a string.
The str_word_count() function counts the number of words in a string.
The strrev() function reverses a string.
The strpos() function searches for a specific text within a string.
The str_replace() function replaces some characters with some other characters in a string.

Conditional Statements :
Conditional statements are used to perform different actions based on different conditions.

if statement executes some code if one condition is true.
if...else statement executes some code if a condition is true and another code if that condition is false.
if...elseif....else statement executes different codes for more than two conditions.

The switch statement is used to perform different actions based on different conditions.
Use switch statement to select one of many blocks of code to be executed.

while loops through a block of code as long as the specified condition is true.
do...while loops through a block of code once, and then repeats the loop as long as the specified condition is true.
for loops through a block of code a specified number of times. It is used when we know in advance how many times the script should run.
foreach loops through a block of code for each element in an array.

Functions :

PHP function is a piece of code that can be reused many times.
It can take input as argument list and return value. There are thousands of built-in functions in PHP.
Besides the built-in PHP functions, we can create our own functions.
A function will not execute immediately when a page loads.
A function will be executed by a call to the function.

Read from User Input and write to user output syntax :

Write to a file :

Read from a file :