Php IF & ELSE

Php IF & ELSE Statemments

Php if, else statements in PHP can perform different actions, based on different conditions.
That means, sometimes you may want to show "bye, have a nice day" instead of "hello how are you?" in user's browser.

syntax :

if (condition)
Code.....
else
Code.....

Example :

$val = 1;
If ($val == 1)
echo "value is one";
else
echo "value is not one";

PHP IF & ELSEIF Statements.
Php elseif Statements is same as elseif statements. But this time you can extend the limit of your conditions.

Syntax :

if (condition)
code ...
elseif (condition)
code ...
elseif (condition)
code...
else
Code :

If ($val = 1)

echo "value is one";
elseif ($val == 2)
echo "value is two";
elseif ($val == 3)
echo "value is three";
else
echo "value is unknown";

Output of above code is :

value is three

Cost

To run ASP programs one needs IIS installed on a Windows platform server, which is not free. PHP programs run on Linux, which is free. Even the connectivity of the database is expensive in the case of ASP as MS-SQL is a product of Microsoft that needs to be purchased. PHP generally uses MySQL, which is freely available.

Performance & tweaking : FOR vs. WHILE vs. DO-WHILE

Base Language

PHP is based on C++ language and the syntax used in PHP is quite similar to C/C++. C/C++ is still considered the best programming language by many programmers and people who love this language would surely feel more comfortable with the syntax of PHP. ASP on the other hand has a more Visual Basic kind of syntax that again is closely related to only Microsoft products. So, it depends on a person-to-person which language he or she is comfortable

Cookies

Storing data at client machine.The expires time is in seconds.

Setting a session cookie
<?php
setcookie('Cookie_name','value','expire_time');
// If expire_time set to 0, or omitted, the cookie will expire at the end of the session (when the browser closes).
?>

Setting a persistant cookie
<?php
setcookie('Cookie_name','value',mktime.time()+60*60); // Expires after 60 min.
?>

Reading a cookie
<?php
echo $_COOKIE['Cookie_name'];
?>

Deleting the Cookies
<?php
setcookie('Cookie_name','',mktime.time()-60); // Set expire time to negative time deletes a cookie.
?>

Other Optional Parameters
Path, Domain, and Secure parameters can also be set to restrict a cookie to a certain path, domain or
in the case of the Secure parameter, limit the cookie to only be set if the request came in over an SSL
connection.

Common Problem : Short expiry cookies depend on users having their system clocks set correctly.
Solution : Don't depend on the users having their clocks set right. Embed the timeout based on your server's
clock in the cookie.
Example:
At the cookie setting script :
<?php
$variable = 'Data to be stored in cookie'; // Data to be store
$value = time()+60 .':'.$varaible; // Concatenate the current(server) time + Data to be store
setcookie('Cookie_name',$value);
?>
At the receiving (getting cookie)script :
<?php
$value = $_COOKIE['Cookie_name']; // Getting the whole string stored in cookie
$valueArray = explode(':',$value);

if($valueArray[0]<=time()){ // Is valid cookie
    $variable = $valueArray[1];
}else{ // Expired cookie
    setcookie('Cookie_name','',mktime.time()-60); // deleting the cookie
}
?>

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