Tuesday, 19 April 2016

Saturday, 16 April 2016

PHP interview questions and answers for freshers

                No comments   
Welcome !!!. In this section we are providing you some frequently asked PHP Interview Questions which will help you to win interview session easily. Candidates must read this section,Then by heart the questions and answers. Also, review sample answers and advice on how to answer these typical interview questions. PHP is an important part of the web world, and every web developer should have the basic knowledge in PHP.Common PHP interview questions, which should help you become a best PHP codder. We hope you find these questions useful. If you are an interviewer, Take the time to read the common interview questions you will most likely be asked.


What is PHP?
PHP is a server side scripting language commonly used for web applications. PHP has many frameworks and cms for creating websites.Even a non technical person can cretae sites using its CMS.WordPress,osCommerce are the famus CMS of php.It is also an object oriented programming language like java,C-sharp etc.It is very eazy for learning.

What is the use of "echo" in php?
It is used to print a data in the webpage, Example: <?php echo 'Car insurance'; ?> , The following code print the text in the webpage

How to include a file to a php page?
We can include a file using "include() " or "require()" function with file path as its parameter.

What's the difference between include and require?
If the file is not found by require(), it will cause a fatal error and halt the execution of the script. If the file is not found by include(), a warning will be issued, but execution will continue.

require_once(), require(), include().What is difference between them?
require() includes and evaluates a specific file, while require_once() does that only if it has not been included before (on the same page). So, require_once() is recommended to use when you want to include a file where you have a lot of functions for example. This way you make sure you don't include the file more times and you will not get the "function re-declared" error.

Differences between GET and POST methods ?
We can send 1024 bytes using GET method but POST method can transfer large amount of data and POST is the secure method than GET method .

How to declare an array in php?
Eg : var $arr = array('apple', 'grape', 'lemon');

What is the use of 'print' in php?
This is not actually a real function, It is a language construct. So you can use with out parentheses with its argument list.
Example print('PHP Interview questions'); 
print 'Job Interview ');

What is use of in_array() function in php ?
in_array used to checks if a value exists in an array

What is use of count() function in php ?
count() is used to count all elements in an array, or something in an object

What’s the difference between include and require?
It’s how they handle failures. If the file is not found by require(), it will cause a fatal error and halt the execution of the script. If the file is not found by include(), a warning will be issued, but execution will continue.

What is the difference between Session and Cookie?
The main difference between sessions and cookies is that sessions are stored on the server, and cookies are stored on the user’s computers in the text file format. Cookies can not hold multiple variables,But Session can hold multiple variables.We can set expiry for a cookie,The session only remains active as long as the browser is open.Users do not have access to the data you stored in Session,Since it is stored in the server.Session is mainly used for login/logout purpose while cookies using for user activity tracking

How to set cookies in PHP?
Setcookie("sample", "ram", time()+3600);

How to Retrieve a Cookie Value?
eg : echo $_COOKIE["user"];

How to create a session? How to set a value in session ? How to Remove data from a session?
Create session : session_start();
Set value into session : $_SESSION['USER_ID']=1;
Remove data from a session : unset($_SESSION['USER_ID'];

what types of loops exist in php?
for,while,do while and foreach (NB: You should learn its usage)

How to create a mysql connection?
mysql_connect(servername,username,password);

How to select a database?
mysql_select_db($db_name);

How to execute an sql query? How to fetch its result ?
$my_qry = mysql_query("SELECT * FROM `users` WHERE `u_id`='1'; "); 
$result = mysql_fetch_array($my_qry);
echo $result['First_name'];

Write a program using while loop.
$my_qry = mysql_query("SELECT * FROM `users` WHERE `u_id`='1'; "); 
while($result = mysql_fetch_array($my_qry))
{
echo $result['First_name'.]."<br/>";
}

How we can retrieve the data in the result set of MySQL using PHP?
1. mysql_fetch_row
2. mysql_fetch_array
3. mysql_fetch_object
4. mysql_fetch_assoc
What is the use of explode() function ?
Syntax : array explode ( string $delimiter , string $string [, int $limit ] ); 
This function breaks a string into an array. Each of the array elements is a substring of string formed by splitting it on boundaries formed by the string delimiter.

What is the difference between explode() and split() functions?
Split function splits string into array by regular expression. Explode splits a string into array by string.

What is the use of mysql_real_escape_string() function?
It is used to escapes special characters in a string for use in an SQL statement

Write down the code for save an uploaded file in php.
if ($_FILES["file"]["error"] == 0)
{
move_uploaded_file($_FILES["file"]["tmp_name"],
      "upload/" . $_FILES["file"]["name"]);
      echo "Stored in: " . "upload/" . $_FILES["file"]["name"]; 
}

How to create a text file in php?
$filename = "/home/user/guest/newfile.txt";
$file = fopen( $filename, "w" );
if( $file == false )
{
echo ( "Error in opening new file" ); exit();
}
fwrite( $file, "This is a simple test\n" );
fclose( $file );

How to strip whitespace (or other characters) from the beginning and end of a string ?
The trim() function removes whitespaces or other predefined characters from both sides of a string.

What is the use of header() function in php ?
The header() function sends a raw HTTP header to a client browser.Remember that this function must be called before sending the actual out put.For example, You do not print any HTML element before using this function.

How to redirect a page in php?
The following code can be used for it, header("Location:index.php");

How stop the execution of a php scrip ?
exit() function is used to stop the execution of a page

How to set a page as a home page in a php based site ?
index.php is the default name of the home page in php based sites

How to find the length of a string?
strlen() function used to find the length of a string

what is the use of rand() in php?
It is used to generate random numbers.If called without the arguments it returns a pseudo-random integer between 0 and getrandmax(). If you want a random number between 6 and 12 (inclusive), for example, use rand(6, 12).This function does not generate cryptographically safe values, and should not be used for cryptographic uses. If you want a cryptographically secure value, consider using openssl_random_pseudo_bytes() instead.

what is the use of isset() in php?
This function is used to determine if a variable is set and is not NULL

What is the difference between mysql_fetch_array() and mysql_fetch_assoc() ?
mysql_fetch_assoc function Fetch a result row as an associative array, While mysql_fetch_array() fetches an associative array, a numeric array, or both

What is mean by an associative array?
Associative arrays are arrays that use string keys is called associative arrays.

What is the importance of "method" attribute in a html form?
"method" attribute determines how to send the form-data into the server.There are two methods, get and post. The default method is get.This sends the form information by appending it on the URL.Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.

What is the importance of "action" attribute in a html form?
The action attribute determines where to send the form-data in the form submission.

What is the use of "enctype" attribute in a html form?
The enctype attribute determines how the form-data should be encoded when submitting it to the server. We need to set enctype as "multipart/form-data" when we are using a form for uploading files

How to create an array of a group of items inside an HTML form ?
We can create input fields with same name for "name" attribute with squire bracket at the end of the name of the name attribute, It passes data as an array to PHP. 
For instance :

<input name="MyArray[]" />  <input name="MyArray[]" />  <input name="MyArray[]" />  <input name="MyArray[]" />
Define Object-Oriented Methodology
Object orientation is a software/Web development methodology that is based on the modeling a real world system.An object is the core concept involved in the object orientation. An object is the copy of the real world enity.An object oriented model is a collection of objects and its inter-relationships

How do you define a constant?
Using define() directive, like define ("MYCONSTANT",150)

How send email using php?
To send email using PHP, you use the mail() function.This mail() function accepts 5 parameters as follows (the last 2 are optional). You need webserver, you can't send email from localhost. eg : mail($to,$subject,$message,$headers);

How to find current date and time?
The date() function provides you with a means of retrieving the current date and time, applying the format integer parameters indicated in your script to the timestamp provided or the current local time if no timestamp is given. In simplified terms, passing a time parameter is optional - if you don't, the current timestamp will be used.

Difference between mysql_connect and mysql_pconnect?
There is a good page in the php manual on the subject, in short mysql_pconnect() makes a persistent connection to the database which means a SQL link that do not close when the execution of your script ends. mysql_connect()provides only for the databasenewconnection while using mysql_pconnect , the function would first try to find a (persistent) link that's already open with the same host, username and password. If one is found, an identifier for it will be returned instead of opening a new connection... the connection to the SQL server will not be closed when the execution of the script ends. Instead, the link will remain open for future use.

What is the use of "ksort" in php?
It is used for sort an array by key in reverse order.

What is the difference between $var and $$var?
They are both variables. But $var is a variable with a fixed name. $$var is a variable who's name is stored in $var. For example, if $var contains "message", $$var is the same as $message.

What are the encryption techniques in PHP
MD5 PHP implements the MD5 hash algorithm using the md5 function,
eg : $encrypted_text = md5 ($msg);

mcrypt_encrypt :- string mcrypt_encrypt ( string $cipher , string $key , string $data , string $mode [, string $iv ] ); 
Encrypts plaintext with given parameters

What is the use of the function htmlentities?
htmlentities Convert all applicable characters to HTML entities This function is identical to htmlspecialchars() in all ways, except with htmlentities(), all characters which have HTML character entity equivalents are translated into these entities.

How to delete a file from the system
Unlink() deletes the given file from the file system.

How to get the value of current session id?
session_id() function returns the session id for the current session.

What are the differences between mysql_fetch_array(), mysql_fetch_object(), mysql_fetch_row()?
Mysql_fetch_array Fetch a result row as an associative array, a numeric array, or both.
mysql_fetch_object ( resource result ) Returns an object with properties that correspond to the fetched row and moves the internal data pointer ahead. Returns an object with properties that correspond to the fetched row, or FALSE if there are no more rows
mysql_fetch_row() fetches one row of data from the result associated with the specified result identifier. The row is returned as an array. Each result column is stored in an array offset, starting at offset 0.
What are the different types of errors in PHP ?
Here are three basic types of runtime errors in PHP:

1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script - for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all - although you can change this default behavior.
2. Warnings: These are more serious errors - for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.
3. Fatal errors: These are critical errors - for example, instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP's default behavior is to display them to the user when they take place.
what is sql injection ?
SQL injection is a malicious code injection technique.It exploiting SQL vulnerabilities in Web applications

What is x+ mode in fopen() used for?
Read/Write. Creates a new file. Returns FALSE and an error if file already exists

How to find the position of the first occurrence of a substring in a string
strpos() is used to find the position of the first occurrence of a substring in a string

What is PEAR?
PEAR is a framework and distribution system for reusable PHP components.The project seeks to provide a structured library of code, maintain a system for distributing code and for managing code packages, and promote a standard coding style.PEAR is broken into three classes: PEAR Core Components, PEAR Packages, and PECL Packages. The Core Components include the base classes of PEAR and PEAR_Error, along with database, HTTP, logging, and e-mailing functions. The PEAR Packages include functionality providing for authentication, networking, and file system features, as well as tools for working with XML and HTML templates.

Distinguish between urlencode and urldecode?
This method is best when encode a string to used in a query part of a url. it returns a string in which all non-alphanumeric characters except -_. have replece with a percentege(%) sign . the urldecode->Decodes url to encode string as any %and other symbole are decode by the use of the urldecode() function.

What are the different errors in PHP?
In PHP, there are three types of runtime errors, they are:

Warnings: 
These are important errors. Example: When we try to include () file which is not available. These errors are showed to the user by default but they will not result in ending the script. 
Notices: 
These errors are non-critical and trivial errors that come across while executing the script in PHP. Example: trying to gain access the variable which is not defined. These errors are not showed to the users by default even if the default behavior is changed. 
Fatal errors: 
These are critical errors. Example: instantiating an object of a class which does not exist or a non-existent function is called. These errors results in termination of the script immediately and default behavior of PHP is shown to them when they take place. Twelve different error types are used to represent these variations internally.


Monday, 11 April 2016

Jquery bind() && unbind() methods

                No comments   
<html>
<head>
<title>bind() event example</title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
<script>
$(document).ready(function(){
$("#b1").click(function(){
$(".one").text("This is Div Content");
$(".one").bind("mouseover",function(){
alert("sdhfj");
});
});
$("#b2").click(function(){
$(".one").unbind("mouseover");
$(".one").text("jquery remove now");
});
});
</script>
<style>
.one
{
width:200px;
height:100px;
background-color:red;
color:#fff;
}
</style>

</head>
<body>
<input type="button" id="b1" value="Start"/>
<input type="button" id="b2" value="Stop"/>
<div class="one">

</div>
</body>
</html>

live() event in jquery

                No comments   
<html>
<head>
<title>live() event example</title>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7/jquery.min.js"></script>
<script>
$(document).ready(function(){
$("p").live("click",function(){
$(this).after("<p>This is Add Paragraph.</p>")
});
});
</script>
</head>
<body>
<p>This is a Paragraph.</p>
</body>
</html>

 Note: If we use $('p').click(function) then the new p can't create new p so for this purpose jquery introduce another concept live().

                No comments   

SQL Aliases

SQL aliases are used to temporarily rename a table or a column heading.

-----------------------------------------------
SQL Alias Syntax for Columns
 SELECT column_name AS alias_name
 FROM table_name;
------------------------------------------------
SQL Alias Syntax for Tables
 SELECT column_name(s)
 FROM table_name AS alias_name;
------------------------------------------------
Display a column in uppercase
SELECT 
  UPPER(firstname),
  lastname
FROM Students   
LIMIT 10

Saturday, 9 April 2016

Top Interview Question For Mysql

                No comments   
What is MySQL? 

 -->MySQL is an open source DBMS which is built, supported and distributed by MySQL AB (now acquired by Oracle).

Why MySQL is used?

 -->MySQL database server is reliable, fast and very easy to use.  This software can be downloaded as freeware and can be downloaded from the internet.

 What are Heap tables?
-->HEAP tables are present in memory and they are used for high speed storage on temporary.

 What is the default port for MySQL Server?
-->The default port for MySQL server is 3306.

 What are the advantages of MySQL when compared with Oracle? 

  1. MySQL is open source software which is available at any time and has no cost involved.
  2. MySQL is portable
  3. GUI with command prompt.
  4. Administration is supported using MySQL Query Browser


Differentiate between FLOAT and DOUBLE? 

 Following are differences for FLOAT and DOUBLE:

  1. Floating point numbers are stored in FLOAT with eight place accuracy and it has four bytes.
  2. Floating point numbers are stored in DOUBLE with accuracy of 18 places and it has eight bytes.

Differentiate CHAR_LENGTH and LENGTH?

CHAR_LENGTH  is character count whereas the LENGTH is byte count. The numbers are same for Latin characters but they are different for Unicode and other encodings.

PHP Interview Question?

                No comments   
What is PHP?

 -->PHP is a web language based on scripts that allows developers to dynamically create generated web pages.

 What does the initials of PHP stand for?

 -->PHP means PHP: Hypertext Preprocessor.

 Which programming language does PHP resemble to?

-->PHP syntax resembles Perl and C.

 What does PEAR stands for?

 PEAR means “PHP Extension and Application Repository”. it extends PHP and provides a higher level of programming for web developers.’

 What is the latest PHP version?

 PHP 7 .
How do you execute a PHP script from the command line?

 Just use the PHP command line interface (CLI) and specify the file name of the script to be executed as follows:
Copy con index.php
CTRL+Z+ENTER
Save file
To run file - php script.php

 How to run the interactive PHP shell from the command line interface?

 Just use the PHP CLI program with the option -a as follows:
php -a
interactive mode enabled
<?php
echo "hello there world!";
phpinfo();
?>
^Z
hit enter)
hello there world!
phpinfo....

 What are the correct and the most two common way to start and finish a PHP block of code?

 The two most  common ways to start and finish a PHP script are: <?php [   —  PHP code—- ] ?> and <? [—  PHP code  —] ?>

 How can we display the output directly to the browser?

 To be able to display the output directly to the browser, we have to use the special tags <?= and ?>.

 What is the main difference between PHP 4 and PHP 5 OR Above Versions?
PHP 5 presents many additional OOP (Object Oriented Programming) features.

 What are PHP magic constants?
PHP provides a large number of predefined constants to any script which it runs.
A few "magical" PHP constants given below −

  • __LINE__                 : The current line number of the file
  • __FILE__                 : The full path and filename of the file
  • __DIR__                   : This prints file full path, without file name
  • __FUNCTION__     : The function name
  • __CLASS__             :  The class name
  • __METHOD__        : The class method name
Example of __LINE__  :

<?php 
// This prints current line number on file
echo "This is line number " . __LINE__ . ".\n";
?>
Example of __FILE__   :
<?php 
 echo "This file full path and file name is '" . __FILE__ . "<br/>";
?>
Example of __DIR__     
:
<?php 
// This prints file full path, without file name
        echo "This file full path is '" . __DIR__ . "'.\n";
?>
Example of __FUNCTION__ 
 :
<?php 
// Really simple basic test function
 function test_function_magic_constant() {
 echo "This is from '" . __FUNCTION__ . "' function.\n";
 }
?>
Example of __CLASS__
 :
<?php 
 // Really simple class for testing magic constants
 class TestMagicConstants {
 // Prints class name
 public function printClassName() {
 echo "This is " . __CLASS__ . " class.\n";
 }
?>
Example of __METHOD__  :
<?php 
// Prints class and method name
 public function printMethodName() {
 echo "This is " . __METHOD__ . " method.\n";
 }
?>
What is the purpose of break statement?

A break statement are used to break to terminated any loop in php.
Example:

<?php
for($i=0;$i<30;$i++)
{
if($i==5){
break;
}
echo $i. "<br/>";
}
How will you get the browser's details using PHP?
<?php
echo $_SERVER['HTTP_USER_AGENT'];
$browser = get_browser();
print_r($browser);
?>
How will you concatenate two strings in PHP?
Using Dot(.) Operator.

Friday, 8 April 2016

What is $() in jQuery library?

                No comments   
What is $() in jQuery library? 

 The $() function is an alias of jQuery() function, at first it looks weird and makes jQuery code cryptic, but once you get used to it, you will love it's brevity. $() function is used to wrap any object into jQuery object, which then allows you to call various method defined jQuery object. You can even pass a selector string to $() function, and it will return jQuery object containing an array of all matched DOM elements. I have seen this jQuery asked several times, despite it's quite basic, it is used to differentiate between developer who knows jQuery or not.

What is HTML?

                No comments   
What is HTML?

 HTML is an acronym which stands for Hyper Text Markup Language. Let's see what is Hyper Text and what is Markup Language?

 Hyper Text: Hyper Text simply means "Text within Text". A text has a link within it, is a hypertext. Every time when you click on a word which brings you to a new webpage, you have clicked on a hypertext.

 Markup language: A markup language is a programming language that is used make text more interactive and dynamic. It can turn a text into images, tables, links etc.

 An HTML document is made of many HTML tags and each HTML tag contains different content.

 Let's see a simple example of HTML.

 <!DOCTYPE>  
<html>  
<body>  
<h1>Write Your First Heading</h1>  
<p>Write Your First Paragraph.</p>  
</body>  
</html>  

Thursday, 7 April 2016

Wednesday, 6 April 2016

Important String Function in PHP

           No comments   
trim() Function
Removes whitespace or other characters from both sides of a string
<?php
$str = "Hello World!";
echo $str . "<br>";
echo trim($str,"Hed!");
?>
ltrim() function

 Removes whitespace or other characters from the left side of a string.
<?php
$str = "Hello World!";
echo $str . "<br>";
echo ltrim($str,"Hello");
?>

 rtrim() function

 Removes whitespace or other characters from the right side of a string.
<?php
$str = "Hello World!";
echo $str . "<br>";
echo rtrim($str,"World!");

 ?>

 strtolower()

 Converts a string to lowercase letters
<?php
echo strtolower("Hello WORLD.");
?>

 strtoupper()

 Converts a string to uppercase letters
<?php
echo strtoupper("Hello WORLD!");

?>

 substr() function

 Returns a part of a string
<?php
echo substr("Hello world",6);
?>

O/P-world 

 substr_replace() function

 Replaces a part of a string with another string.
<?php
echo substr_replace("Hello","world",0); // 0 will start replacing at the first character in the string

?>

sha1() function

 Calculates the SHA-1 hash of a string
<?php
$str = "Hello";
echo sha1($str);
?>

 md5() function

 Calculates the MD5 hash of a string
<?php
$str = "Hello";
echo md5($str);
?>

 strlen() function

 Returns the length of a string
<?php
echo strlen("Hello");
?>

 strpos() function

 The strpos() function finds the position of the first occurrence of a string inside another string.
<?php
echo strpos("I love php, I love php too!","php");

?>  

String in PHP

           No comments   

A string is series of characters, where a character is the same as a byte. This means that PHP only supports a 256-character set, and hence does not offer native Unicode support. See details of the string type.
A string literal can be specified in four different ways:
1.single quoted
2.double quoted
3.heredoc syntax
4.nowdoc syntax 
Define  String With single quoted & double quoted
<?php 
$t1="My Name is Virendra<br/>";
$t2="My Name is Virendra";
echo $t1;
echo $t2;

?>

 Difference between single quote and double quote string in php.
A single-quoted string does not have variables within it interpreted. A double-quoted string does.

The single-quoted strings are faster at runtime because they do not need to be parsed.

 Define  String heredoc syntax quoted & nowdoc syntax
As you see the heredoc starts with the <<< operator and an identifier. 
<?php
   $str = <<<DEMO
    This is a
    demo message
   with heredoc.
   DEMO; 
   echo $str;

?>
Nowdoc syntax is similar to heredoc. The only difference is that the delimiter is enclosed within single quotes:
Syntax:
$myString =  <<< 'DELIMITER' 
         (insert string here) 

DELIMITER;  
Traditionally, heredoc & nowdoc delimiters are written in uppercase, like constants.

Tuesday, 5 April 2016

PHP 5 File Upload

           No comments   
<?php
$target_dir = "uploads/";
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
$uploadOk = 1;
$imageFileType = pathinfo($target_file,PATHINFO_EXTENSION);
// Check if image file is a actual image or fake image
if(isset($_POST["submit"])) {
    $check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);
    if($check !== false) {
        echo "File is an image - " . $check["mime"] . ".";
        $uploadOk = 1;
    } else {
        echo "File is not an image.";
        $uploadOk = 0;
    }
}
// Check if file already exists
if (file_exists($target_file)) {
    echo "Sorry, file already exists.";
    $uploadOk = 0;
}
// Check file size
if ($_FILES["fileToUpload"]["size"] > 500000) {
    echo "Sorry, your file is too large.";
    $uploadOk = 0;
}
// Allow certain file formats
if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"
&& $imageFileType != "gif" ) {
    echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";
    $uploadOk = 0;
}
// Check if $uploadOk is set to 0 by an error
if ($uploadOk == 0) {
    echo "Sorry, your file was not uploaded.";
// if everything is ok, try to upload file
} else {
    if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
        echo "The file ". basename( $_FILES["fileToUpload"]["name"]). " has been uploaded.";
    } else {
        echo "Sorry, there was an error uploading your file.";
    }
}
?>

PHP - Sessions

           No comments   
Make test.php in your root folder.

<?php
   session_start();
   if( isset( $_SESSION['counter'] ) ) {
      $_SESSION['counter'] += 1;
   }else {
      $_SESSION['counter'] = 1;
   }
   $msg = "You have visited this page ".  $_SESSION['counter'];
   $msg .= "in this session.";
?>
<html>
   <head>
      <title>Setting up a PHP session</title>
   </head>
   <body>
      <?php  echo ( $msg ); ?>
   </body>
</html>

What is the difference between $message and $$message?

           No comments   

It is a classic example of PHP’s variable variables. take the
following example.$message = “Mizan”;$$message = “is a moderator of PHPXperts.”;$message is a simple PHP variable that we are used to. But the
$$message is not a very familiar face. It creates a variable name $mizan
with the value “is a moderator of PHPXperts.” assigned. break it like
this${$message} => $mizanSometimes it is convenient to be able to have variable variable
names. That is, a variable name which can be set and used dynamically.

What is the difference between mysql_fetch_object and mysql_fetch_array?

           No comments   
mysql_fetch_object() is similar tomysql_fetch_array(), with one difference –
an object is returned, instead of an array. Indirectly, that means that
you can only access the data by the field names, and not by their
offsets (numbers are illegal property names).

Monday, 4 April 2016

Functions in PHP

           No comments   
  1. Besides control and variables are PHP scripts through function calls. If the same code is executing this program code is often outsourced to a function. So instead of having the same code every time you call in the appropriate places on only the function, which then performs the actual work.
    The behavior of a function is affected by their parameters. A function can have any number of parameters, including parameters not exactly as an infinite number of parameters. Further, a function return value. This is also the standard use of a function, it will pass parameters and the function returns a value based on this back. For example, the sin function returns the sine of the given radian value.
    <?php
    sin(3.1415);
    ?>
  2. Define your own functions
    Sooner or later we want not only the functionality provided by using special PHP define your own functions. A function definition starts with the keyword function in PHP.
    <? Php
    function
    ?>
    This is followed by the actual name of the function. The name itself is subject to common rules such as not begin with numbers. Furthermore, the functions have two underscores (__) begin special functionality. You should use this function only when they want exactly the functionality that is described in the manual.
    <? Php
    function myFunction
    ?>
    Like a function call now follows an open parenthesis (. According to the clamp can now variables for the parameters are given. With the number of variables (comma separated) so you need to decide the number of parameters. However if you are planning a function with any to define many parameters you are at this point no parameters at all and use the functions in the function body func_get_args, func_get_arg and func_num_args. The parameter list is then finished with the closing parenthesis).
    <? Php
    function myFunction ($ param1, $ param2)
    ?>
    The contents of the function starts with an opening curly brace {. Now you can write any PHP code. At the end of the function body ends with a closing curly chamber }.
    <? Php
    function myFunction ($ param1, $ param2) {
       / / Here now follows
       / / Normal php code
    }
    ?>
    For typical programming style to indent the code within the function by 4 spaces. Thus it can be seen where the function starts (the function keyword) and where it ends (at the closing brace}).
    Within the function, the parameter variables can be used. In addition to the superglobal variables no further variables are otherwise available. This is called also variable scope. The variable parameters are then filled in accordance with the values ​​of the function call. If the parameters for the function are variables whose values ​​are passed, but not the variable itself in first place, it is therefore not possible to change variables that are used outside the function.
    <? Php
    function myFunction () {
       echo $ var / / help, where is defined $ var?
    }
    $ Var = 'HTML';
    myFunction () / / will not work because the only function parameters and variables
                    / / Super globals are available
    ?>
    3 Optional parameters
    In PHP, it is allowed to define which one is not used later in a function call parameters. Thus it is e.g. possible to call the function although theoretically supports 3 parameters a function with only one parameter. So as to define a function assigns default values ​​to the parameters in the parameter list. It is done by specifying an assignment for the parameter. When the function is called with a parameter value that is used for the variable parameters. When the function is called without the parameter as the parameter variable contains the specified default value.
    <? Php
    function myFunction ($ x, $ test = 'foobar') {
       echo 'x has the value: "' $ x.. '" test and has the value: "' $ test.. '"';
    }
    myFunction (4, 'word') / / outputs 4 and word of
    myFunction (5) / / outputs 5 and foobar
    myFunction () / / not possible since at least one parameter is required
    myFunction (1, 2, 3) / / possible, but the third parameter is lost
    ?>
    4 Return value of functions
    Although you use any functions in PHP code, as well as echo, it is customary return a calculated value for a function. This is implemented in PHP with the language construct return. It got to a value or a variable that you want to return.
    <? Php
    function myFunction () {
       do_that () / / is still running
       return 300;
       mach_das () / / is not running, as was leaving the function / closed
    }
    echo myFunction () / / outputs 300 from
    ?>
    With the return function is terminated at the same time. This can be done at any point, if it makes sense. In calculating the sine of the value 0 for example be expected not great but there is a case distinction quite early to the value 0 is returned.
    It is also possible to exit a function and return with it to indicate no return value. This makes only sense if not expected is that a function has a return value.
    <? Php
    function myFunction () {
       / / Code anderere
       return;
    }
    myFunction () / / works without problems
    My $ var = function () / / works, $ var got the value NULL (a special data type)
    ?>
    5 Documentation of own functions
    Functions that are provided by PHP described in detail on the official website. Accordance with specially created features missing such a documentation. You may guess the functionality of the function name. For complex functions are hoping for a good documentation. For this purpose they PHPDocs. Before the actual function to add a PHPDoc comment which describes the function.
    <? Php
    / **
    * Returns a square number.
    *
    * This function is passed a parameter and returns
    * Square of this function back.
    *
    * @ Param x The value of the you want to have a perfect square
    * @ Return The number of square
    * /
    function square ($ x) {
       return $ x * $ x;
    }
    ?>

Arrays in PHP

           No comments   
An array is a collection of values in a single variable name.The variables in an array is called the array elements.Array elements are accessed using a single name and an indexed number represending the postion of the elements with in the array.The lenght of an array will be less than the actual length.Since index is starts with zero.We can insert the values for each elemnets in an array by using a subscript as follows,
<?php
$a [0] = "apple";
$a [1] = "cherry";
$a [2] = "plum";
?>
We can also use array() function to declare an array of predifined values
<?php
$a = array("apple","cherry","plum");
?>
Values taken from the array is similar to assign values to the array.
<?php
$abc = $a[2];
?>
Now the value of the variable $abc will be "plum" , Loops are widely used to manipulate the arrays.The following code is used for assigning and printing the values in an array.
<?php
for($i=1;$i<=10;$i++) { $arr [$i] = $i*$i; echo $arr [$i]; }
?>
There are three types of arrays in php:-
  1. Numeric(Indexed) array - An array with a numeric index
  2. Associative array - An array where each ID key is associated with a value
  3. Multidimensional array - An array containing one or more arrays

Numeric Array

Numeric or Indexed array has numeric keys that start with zero.Any kind of values can be assigned in the elements of the array.The following code shows how to assigning values to an indexed array. 
<?php
$a = array("apple","cherry","plum"); 
?>
Or 
<?php
$a [0] = "apple";
$a [1] = "cherry";
$a [2] = "plum"; 
?>

Associative Array

In associative array we can use user defined keys (named keys) for assigning values to the array.The usage of associative array is given below. 
<?php
$a["apple"]="Rs.72";
$a["grape"]="Rs.152";
$a["cherry"]="Rs.350"; 
?>

Multidimensional Array

A multidimensional array is an array that contains at least one other array as the value of one of the indexes.
<?php
$MDA= array(
"A" => array(0 => "red", 2 => "blue", 3 => "green"),
"B" => array(1 => "orange", 2 => "black"),
"C" => array(0 => "white", 4 => "purple", 8 => "grey")
);

echo $MDA["A"][3]; // green
echo "<br>";
echo $MDA["C"][8]; // grey
?>