In web programming, sometimes we need to get the domain name out of the url. Here how to do it:

<?php
// get host name from URL
preg_match(‘@^(?:http://)?([^/]+)@i’, “http://www.php.net/index.html“, $matches);
$host = $matches[1];

// get last two segments of host name
preg_match(‘/[^.]+\.[^.]+$/’, $host, $matches);
echo “domain name is: {$matches[0]}\n”;
?>

What’s the hell that code means!

Here are list of functions that can be used to find a certain character in a string.

• preg_match()
  if (preg_match(“/php/i”, $string)) {
  echo “A match was found. The string contains ‘php’ “;
  } else {
  echo “A match was not found.”;
  }
• ereg()
  if(ereg(‘ ‘,$string)) echo ‘you have spaces’;
  else echo ‘no spaces!’;
• eregi()
  if (eregi(‘z’, $string)) {
  echo “‘$string’ contains a ‘z’ or ‘Z’!”;
  }
• strpos()
  if(strpos($string, ‘ ‘)) echo ‘you have spaces’;
  else echo ‘no spaces’;

I have a form for user to submit information. I need to makesure user entering numeric value for numeric field but not character string and viceversa I need to makesure user not entering numeric value for field that require character string value. I do it after user click on ’submit’.

Let’s say the field is called zipcode.

if ( isset($_POST['zipcode']) && is_numeric($_POST['zipcode'])
&& is_int($_POST['zipcode'] + 0)
)

To check if the input is numeric, We use is_numeric() function, and if it is numeric we cast it as a number by adding zero (or multiplying by 1) and check to see whether the number is an integer or a float.