unset() and empty() functions in PHP

By: Emiley J. Emailed: 1698 times Printed: 2200 times    

Latest comments
By: rohit kumar - how this program is work
By: Kirti - Hi..thx for the hadoop in
By: Spijker - I have altered the code a
By: ali mohammed - why we use the java in ne
By: ali mohammed - why we use the java in ne
By: mizhelle - when I exported the data
By: raul - no output as well, i'm ge
By: Rajesh - thanx very much...
By: Suindu De - Suppose we are executing

unset()

unset() "undeclares" a previously set variable, and frees any memory that was used by it if no other variable references its value. A call to isset() on a variable that has been unset() returns false.

For example:

$name = "John Doe";

unset($name);

if (isset($name)) {

print ’$name is set';

}

This example will not generate any output, because isset() returns false. unset() can also be used on array elements and object properties similar to isset().

empty()

empty() may be used to check if a variable has not been declared or its value is false. This language construct is usually used to check if a form variable has not been sent or does not contain data. When checking a variable’s truth value, its value is first converted to a Boolean according to the rules in the following section, and then it is checked for true/false.

For example:

if (empty($name)) {

print 'Error: Forgot to specify a value for $name';

}

This code prints an error message if $name doesn’t contain a value that evaluates to true.

 


PHP Home | All PHP Tutorials | Latest PHP Tutorials

Sponsored Links

If this tutorial doesn't answer your question, or you have a specific question, just ask an expert here. Post your question to get a direct answer.



Bookmark and Share

Comments(0)


Be the first one to add a comment

Your name (required):


Your email(required, will not be shown to the public):


Your sites URL (optional):


Your comments:



More Tutorials by Emiley J.
Error generating R.java from manifest
ERROR 1251: Client does not support authentication protocol requested by server; consider upgrading MySQL client
IIS and Tomcat - how to configure to work together
PHP Warning: Unknown(): Unable to load dynamic library '/usr/local/php4/lib/php/extensions/no-debug ......
Adding your own Application icon for your J2ME application (jar file)
Creating Menus in Code using VB.net
Traversing all files in a directory using Ruby
Using Proxy to connect to URLs in Ruby
POST a form in Ruby
Reading URL content using Ruby (HTTP)
dRuby client/server mode sample program
Benchmark module in Ruby
encoding and decoding in Ruby using Base64 Module
Module Abbrev in Ruby
Standard Library Packages in Ruby

More Tutorials in PHP
PHP code to import from CSV file to MySQL
PHP code to write to a CSV file from MySQL query
PHP code to write to a CSV file for Microsoft Applications
Convert XML to CSV in PHP
Password must include both numeric and alphabetic characters - Magento
PHP file upload (Large Files)
PHP file upload prompts authentication for anonymous users
PHP file upload with IIS on windows XP/2000 etc
Error: Length parameter must be greater than 0
Multiple File Upload in PHP using IFRAME
Resume or Pause File Uploads in PHP
Exception in module wampmanager.exe at 000F15A0 in Windows 8
Handling file locks in PHP
HTML table output using Nested for loops in PHP
Count occurrences of a character in a String in PHP

More Latest News
Most Viewed Articles (in PHP )
isset() function in PHP
Convert IP address to integer and back to IP address in PHP
Using Text file as database in PHP
Traversing Arrays Using foreach in PHP
public, protected, and private Properties in PHP
parent:: AND self:: in PHP
Using Cookies in PHP
preg_replace() and preg_replace_callback() in PHP
preg_split() and explode() in PHP
GDBM, NDBM, DB2, DB3, DBM, and CDB Databases in PHP
Parent: child process exited with status 3221225477 -- Restarting
A Basic Example using PHP in AWS (Amazon Web Services)
Where does the PHP run?
Function to return number of digits of an integer in PHP
Retrieve multiple rows from mysql and automatically create a table in PHP
Most Emailed Articles (in PHP)
Traversing Arrays Using foreach in PHP
preg_split() and explode() in PHP
GDBM, NDBM, DB2, DB3, DBM, and CDB Databases in PHP
Sorting an Array in PHP
fixEncoding in PHP
Assignment operators in PHP
switch Statements in PHP
preg_match(), function preg_match_all(), preg_grep() in PHP
Reading .CSV file in PHP
Encrypting files using GnuPG (GPG) via PHP
Where does the PHP run?
Setting up PHP in Windows 2003 Server IIS7, and WinXP 64
Perl's Encoding::FixLatin equivalent in PHP
break out of an if() block in PHP
PHP file upload with IIS on windows XP/2000 etc