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Php


#1

Functions and argument in php.



Arguments

Functions can be handed

variables, so that you can do

something with what’s inside of

them. You pass the variable over

to your functions by typing them

inside of the round brackets of

the function name. Here’s a script

similar to the one you saw

earlier:

<?PHP
$error_text = "Error message";
display_error_message
($error_text);
function display_error_message
($error_text) {
print $error_text;
}
?>

The only difference is the that we

now have something between

the round brackets of our

function:

function display_error_message

( $error_text) {

}

The name is the same, but we’ve

put a variable in between the

round brackets. This is the

variable that we want to do

something with. The one called

$error_text. By typing a variable

inside of the round brackets, you

are setting up something called

an argument. An argument is a

variable or value that you want

your function to deal with.

Notice how the function is called:

$error_text = “Error message”;

display_error_message

( $error_text);

The first line puts something into

the variable. But when you want

to hand something to a function

that has an argument, you need

to type it between the round

brackets of the function call. In

our script, we’re typing the name

of the variable. But this would do

just as well:

display_error_message(“Error

message”);

Here, we’re putting direct text

between the round brackets.

That works ok. But try it like this:

$error_text = “Error message”;

display_error_message( );

You’ll get an error message from

PHP. Something like this:

"Warning: Missing argument 1

for display_error_message( )"

That’s telling you that your

function has been set up to take

an argument, but that you’ve left

the round brackets empty when

you tried to call the function.

Your functions can have more

than 1 argument. Just separate

each argument with a comma.

Like this:

function error_check($error_text,

error_flag) {

}

To call this function, you’d then

need to hand it two arguments:

$error_text = “Error message”;

error_flag = 1;

error_check($error_text,

error_flag);

If you only hand the above

function 1 argument, you’d get

error messages from PHP.

So, to recap:

To pass something to a function,

create an argument

To call a function that has an

argument, don’t leave the round

brackets empty





To learn more about PHP, feel free to contact dprogrammer