PHP

PHP Variable Scope

 

 

There’s a thing called scope in programming. This refers to where in your scripts
a variable can be seen. If a variable can bee seen from anywhere, it’s said
to have global scope. In PHP, variables inside of functions can’t be seen from
outside of the function. And functions can’t see variables if they are not part
of the function itself. Try this variation of our script as an example:

<?PHP

$error_text = “Error Detetceted”;

display_error_message();

function display_error_message( ) {

print $error_text;

}

?>

This time, we have set up a variable called $error_text to hold the
text of our error message. This is set up outside of the function. Run the script,
and you’ll get a PHP error message about ” Undefined variable”.

Likewise, try this script:

<?PHP

display_error_message();

print $error_text;

function display_error_message() {

$error_text = “Error message”;

}

?>

This time, the variable is inside the function, but we’re trying to print it
from outside the function. You still get an error message. Here’s a correct
version:

<?PHP

display_error_message();

function display_error_message() {

$error_text = “Error message”;
print $error_text;

}

?>

Here, we have both the variable and the print statement set up inside of the
function. The error message now prints.

So if you need to examine what is inside of a variable, you need a way to get
the variable to the function. That’s where arguments come in. We’ll explore
arguments in the next part.

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