PHP Questions and Answers

Any time you have an array with more than one dimension, complex parsing syntax is required. print “Contents: {$arr[1][2]}” would’ve worked.

htmlspecialchars only takes care of , single quote ‘, double quote ” and ampersand.

htmlentities translates all occurrences of character sequences that have different meaning in HTML.

The major difference is the length of the hash generated. CRC32 is, evidently, 32 bits, while sha1() returns a 128 bit value, and md5() returns a 160 bit value. This is important when avoiding collisions.

The syntax for repairing a MySQL table is:

REPAIR TABLE tablename
REPAIR TABLE tablename QUICK
REPAIR TABLE tablename EXTENDED

This command will repair the table specified.
If QUICK is given, MySQL will do a repair of only the index tree.
If EXTENDED is given, it will create index row by row.

Anwser 1:
$message is a simple variable whereas $$message is a reference variable. Example:
$user = ‘user01’

is equivalent to

$holder = ‘user’;
$$holder = ‘user01’;

Anwser 2:

They are both variables. But $message is a variable with a fixed name. $$message is a variable who’s name is stored in $message. For example, if $message contains “var”, $$message is the same as $var.

Anwser 1:
urlencode() returns the URL encoded version of the given string. URL coding converts special characters into % signs followed by two hex digits. For example: urlencode(“10.00%”) will return “10%2E00%25”. URL encoded strings are safe to be used as part of URLs.
urldecode() returns the URL decoded version of the given string.

Anwser 2:

string urlencode(str) – Returns the URL encoded version of the input string. String values to be used in URL query string need to be URL encoded. In the URL encoded version:

Alphanumeric characters are maintained as is.
Space characters are converted to “+” characters.
Other non-alphanumeric characters are converted “%” followed by two hex digits representing the converted character.

string urldecode(str) – Returns the original string of the input URL encoded string.

For example:

$discount =”10.00%”;
$url = “http://domain.com/submit.php?disc=”.urlencode($discount);
echo $url;

You will get “http://domain.com/submit.php?disc=10%2E00%25”.

Once the Web server received the uploaded file, it will call the PHP script specified in the form action attribute to process them.

This receiving PHP script can get the uploaded file information through the predefined array called $_FILES.

Uploaded file information is organized in $_FILES as a two-dimensional array as:

$_FILES[$fieldName][‘name’] – The Original file name on the browser system.
$_FILES[$fieldName][‘type’] – The file type determined by the browser.
$_FILES[$fieldName][‘size’] – The Number of bytes of the file content.
$_FILES[$fieldName][‘tmp_name’] – The temporary filename of the file in which the uploaded file was stored on the server.
$_FILES[$fieldName][‘error’] – The error code associated with this file upload.

The $fieldName is the name used in the <input type=”file” name=”<?php echo $fieldName; ?>”>.

Just run the PHP CLI (Command Line Interface) program and provide the PHP script file name as the command line argument.

For example, “php myScript.php”, assuming “php” is the command to invoke the CLI program.

Be aware that if your PHP script was written for the Web CGI interface, it may not execute properly in command line environment.

Total 5 types of tables we can create
1. MyISAM
2. Heap
3. Merge
4. INNO DB
5. ISAM
MyISAM is the default storage engine as of MySQL 3.23. When you fire the above create query MySQL will create a MyISAM table.