28.4. The syntax of PHP code

28.4.1. Variables

Variables are those elements that are given variable values, depending on the case. Here is an example:

<? 
if ($foobar == 1)){ 
 echo "The value is 1"; 
} else {
 echo "The value is not 1"; 
}
?> 

See also PHP variables.

28.4.2. Functions

Here is an example of a simple PHP function:

function get_lang($module) {
  global $currentlang, $language;
 
  HERE GOES THE FUNCTION CODE
}

It has the following structure, common to every PHP function:

• the function name, preceded by the keyword "function",

• the function parameters in the parenthesis,

• the global variables that we intend to use in this function, registered through the "global" keyword (we cannot use any global variables, if we do not register them as such),

• the curly brackets that include the function's content

Functions may be called from anywhere in the PHP code. See also PHP functions.

28.4.3. Switches

A switch in PHP allows us to take certain actions depending on the value of a certain variable, as in the following example, where we check the value of the $pa variable:

switch($pa) {
  case "showpage":
    showpage($pid, $page);
  break;
  case "list_pages_categories":
    list_pages_categories($cid);
  break;
  default:
    list_pages();
  break;
}

In case $pa has the value “showpage”, we call the showpage() function, in case it has the value "list_pages_categories", we call the list_pages_categories() function. If $pa does not have any of these two values, or any value at all, we enter the default case and call list_pages(). See also PHP control structures.

Switch statements are often used in module development (especially in the module administration functions, see Section 21.4). So, if you declared in a module admin case file a switch like:

switch($func) {
     case "func-one":
     funct-one();
     break;    
}

you must call it through a link like:

http://www.yoursite.com/modules.php?mop=modload
&name=The_Web_Ring&file=index&func=func-one

If your function needs to have parameters (see Section 28.4.2), your switch will look like:

switch($func) {
    case "func-one":
    funct-one($xid, $xname);
    break;
}

and your link will have to be:

http://www.yoursite.com/modules.php?mop=modload
&name=The_Web_Ring&file=index&func=func-one&xid=$xid&xname=$xname

See also the ADDONS-MODULES file that came with your PHP-Nuke package.