File: hello.php

      
      
      
    Hello by PHP";  
    ?>  
      
       
 

      
Output:
Hello by PHP
 
 

      
Syntax:

    void echo ( string $arg1 [, string $... ] )   
 

      
Syntax:

    int print ( string $arg)   
 

      
$variableName=value;   
 

      

    Using define() function
    Using const() function
 
 

      

    Scalar types
    Compound types
    Special types
 
 

      

    Using // (C++ style single line comment)
    Using # (Unix Shell style single line comment)
 
 

      
PHP multi-line comment is made by enclosing all lines within. 
 

      
php script.php 
 

      
php -a 
 

      
 and  
 

      
www.url.com?var=value
$variable = $_GET["var"]; this will now contain 'value' 
 

      
$_POST["var"]; 
 

      
    bool move_uploaded_file ( string $filename , string $destination )     
 

      
    int readfile ( string $filename )      
 

      
    bool mail($to,$subject,$message,$header);     
 

      
    resource mysqli_connect (server, username, password)        
 

      

    mysqli_query()
    PDO::_query()
 
 

      

    Notices:These are non-critical errors. These errors are not displayed to the users.
    Warnings:These are more serious errors, but they do not result in script termination. By default, these errors are displayed to the user.
    Fatal Errors:These a 
 

      
 syntax of closing tag in PHP 
 

      

    Establish a connection to MySQL server from your PHP script.
    If the connection is successful, write a SQL query to create a database and store it in a string variable.
    Execute the query.
 
 

      
parent::constructor($value) 
 

      
$variable1 = 'Hello ';

$variable2 = 'World';

$variable3 = $variable1.$variable2;