1. How to extract a file extension in php?

Old method was
$path_info = pathinfo('/images/myPicture.gif');
echo $path_info['extension']; //will print gif

New way is
$filename = '/images/myPicture.gif';
$ext = pathinfo($filename, PATHINFO_EXTENSION);
echo $ext;//will print gif

2. How to use cryptographic security in php?

If you need some pseudorandom bits for security or cryptographic purposes (e.g.g., random IV for block cipher, random salt for password hash) mt_rand() is a poor source. On most Unix/Linux and/or MS-Windows platforms you can get a better grade of pseudorandom bits from the OS or system library, like this:

// get 128 pseudorandom bits in a string of 16 bytes

$pr_bits = '';

// Unix/Linux platform?
$fp = @fopen('/dev/urandom','rb');
if ($fp !== FALSE) {
$pr_bits .= @fread($fp,16);

// MS-Windows platform?
if (@class_exists('COM')) {
// http://msdn.microsoft.com/en-us/library/aa388176(VS.85).aspx
try {
$CAPI_Util = new COM('CAPICOM.Utilities.1');
$pr_bits .= $CAPI_Util->GetRandom(16,0);

// if we ask for binary data PHP munges it, so we
// request base64 return value. We squeeze out the
// redundancy and useless ==CRLF by hashing...
if ($pr_bits) { $pr_bits = md5($pr_bits,TRUE); }
} catch (Exception $ex) {
// echo 'Exception: ' . $ex->getMessage();

if (strlen($pr_bits) < 16) {
// do something to warn system owner that
// pseudorandom generator is missing
NB: it is generally safe to leave both the attempt to read /dev/urandom and the attempt to access CAPICOM in your code, though each will fail silently on the other's platform. Leave them both there so your code will be more portable.

3. How To Read the Entire File into a Single String?

If you have a file, and you want to read the entire file into a single string, you can use the file_get_contents() function. It opens the specified file, reads all characters in the file, and returns them in a single string. Here is a PHP script example on how to file_get_contents():

$file = file_get_contents("/windows/system32/drivers/etc/services");
print("Size of the file: ".strlen($file)."n");

This script will print:

Size of the file: 7116

4. How many ways can we get the value of current session id?

session_id() returns the session id for the current session.

5. What is 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.

6. Explain the ternary conditional operator in PHP?

Expression preceding the ? is evaluated, if it's true, then the expression preceding the : is executed, otherwise, the expression following : is executed.

7. How To Turn On the Session Support in PHP?

The session support can be turned on automatically at the site level, or manually in each PHP page script:

* Turning on session support automatically at the site level: Set session.auto_start = 1 in php.ini.
* Turning on session support manually in each page script: Call session_start() funtion.

8. How can I embed a java program in php file and what changes have to be done in php.ini file?

There are two possible ways to bridge PHP and Java: you can either integrate PHP into a Java Servlet environment, which is the more stable and efficient solution, or integrate Java support into PHP. The former is provided by a SAPI module that interfaces with the Servlet server, the latter by this Java extension.
The Java extension provides a simple and effective means for creating and invoking methods on Java objects from PHP. The JVM is created using JNI, and everything runs in-process.

Example Code:

getProperty('java.version') . ''; echo 'Java vendor=' . $system->getProperty('java.vendor') . ''; echo 'OS=' . $system->getProperty('os.name') . ' ' . $system->getProperty('os.version') . ' on ' . $system->getProperty('os.arch') . ' '; // java.util.Date example $formatter = new Java('java.text.SimpleDateFormat', "EEEE, MMMM dd, yyyy 'at' h:mm:ss a zzzz"); echo $formatter->format(new Java('java.util.Date')); ?>

The behavior of these functions is affected by settings in php.ini.
Table 1. Java configuration options
Name Default Changeable

9. Explain about Type Juggling in php?

PHP does not require (or support) explicit type definition in variable declaration; a variable's type is determined by the context in which that variable is used. That is to say, if you assign a string value to variable $var, $var becomes a string. If you then assign an integer value to $var, it becomes an integer.

An example of PHP's automatic type conversion is the addition operator '+'. If any of the operands is a float, then all operands are evaluated as floats, and the result will be a float. Otherwise, the operands will be interpreted as integers, and the result will also be an integer. Note that this does NOT change the types of the operands themselves; the only change is in how the operands are evaluated.

$foo += 2; // $foo is now an integer (2)
$foo = $foo + 1.3; // $foo is now a float (3.3)
$foo = 5 + "10 Little Piggies"; // $foo is integer (15)
$foo = 5 + "10 Small Pigs"; // $foo is integer (15)

If the last two examples above seem odd, see String conversion to numbers.
If you wish to change the type of a variable, see settype().
If you would like to test any of the examples in this section, you can use the var_dump() function.
Note: The behavior of an automatic conversion to array is currently undefined.

Since PHP (for historical reasons) supports indexing into strings via offsets using the same syntax as array indexing, the example above leads to a problem: should $a become an array with its first element being "f", or should "f" become the first character of

10. What is the difference between Reply-to and Return-path in the headers of a mail function?

Reply-to: Reply-to is where to delivery the reply of the mail.

Return-path: Return path is when there is a mail delivery failure occurs then where to delivery the failure notification.

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