define()

[dclamp]

What is define used for? It is for defining constants but why not just use a string?

[DigiRev]

You could just use a variable, but when I make something like a vars.php file to store settings, I personally use define().

Also, since "definitions"/constants, whatever, don't require you to use a $ sign, it helps distinguish them from other variables.

<?php
  define('DB_HOST','localhost');
  define('DB_USER','username');
  define('DB_PASS','password');
  define('DB_NAME','digirev');

  function db_connect() {
    $f_dbc = @mysql_connect(DB_HOST,DB_USER,DB_PASS) or die(mysql_error());
    mysql_select_db(DB_NAME) or die(mysql_error());
    return $f_dbc;
  }
?>

[dclamp]

so there is really no difference to using defined constants and strings?

i think they look alot better than strings, personally.

thanks Digi!

[DigiRev]

so there is really no difference to using defined constants and strings?

i think they look alot better than strings, personally.

thanks Digi!

You're welcome.

Edit: There seems to be a few differences that I didn't think of, like placing one directly in a string.

echo "DB host is $DB_HOST"; // would work if $DB_HOST was a variable
echo "DB host is DB_HOST"; // will not work with constant 

And there's also a case-sensitive argument in Define().

You may want to look here for more info:
http://us3.php.net/define

[visualAd]

A constant remains constant unlike a variable which can be changed. Once a constant is defined it cannot be changed. Constants are usually defined at design time but in PHP global constants can be defined at run time and given dynamic values (i.e: expressions containing values derived from mathematical operations, functions or variables).

Class constants are however are real constants as they can only be defined at design time and must be a constant expression only.

define ('MY_CONST', 1); // valid
define ('MY_CONST1', $GLOBALS['my_var']); // valid

class Test
{
    const MY_CONST = 1; // ok
    const MY_CONST1 = $GLOBALS['my_var']; // invalid
} 

[dclamp]

ah! that makes sense.

thanks for elaborating va