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PHP Functions

1. How do I get a user's IP address?

<?
$domain = GetHostByName ( $REMOTE_ADDR );
?>

2. How do I insert javascript in php code?

<?
echo "<script language=\"JavaScript\">\n" ;
echo "alert(" javascript from php ");\n" ;
echo "</script>" ;
?>

3. How do I generate a random number from php?

To generate a random number between 0 and 100 do this:

srand((double)microtime()*1000000);
echo rand(0,100);

4. How do I check whether a string contains HTML?

There are two ways you can do it, one is using a regular expression the other is comparing strings.

First the regular expression approach:

if (preg_match("/([\<])([^\>]{1,})*([\>])/i", $string)) {
     echo "string contains html";
}

And here is the other approach:

if(strlen($string) != strlen(strip_tags($string)){
   echo "string contains HTML";
}

5. How do I find out weather a number is odd or even?

$i = 10;
if ( $i&1 )
{
     echo "$i is odd";
}
else
{
     echo "$i is even";
}

6. How do I set the browser timeout?

If your script is too complex to finish within the standard 30 seconds you can set a new value with the function:

set_time_limit(900);

this sets the timeout too 900 seconds / 15 minutes.

7. How do I get the Filename out of a directory name?

Use strrpos - same as strpos but in reverse. Find the last occurence of '/' then move forward one position and then substr from that position onwards to the end of the string.

<?php echo substr($url,strrpos($url,'/')+1); ?>

8. How do I remove all characters from within curly brackets or square brackets?

Use preg_replace and regular expressions. The examples below remove everything in a string that is within curly braces or square brackets.

echo preg_replace(" (\[.*?\])",'',"King Kong [2005]");
echo preg_replace(" (\(.*?\))",'',"King Kong (Amazing Box Set)");

9. How can I remove a trailing character in a string, remove last occurence of a character?

Use the SUBSTR command:

$strWithoutLastChar = substr("abcdef", 0, -1); 

This will return "abcde"