Any variable declared within a function will have a scope limited to the function. It's known as a local variable. It will not be available outside the function or within other functions.
Similarly, a variable delcared outside a function will not automatically be available within it.
In large projects, this can save you from accidentally overwriting the contents of a variable when you declare two variables with the same name in separate functions.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="EN" lang="EN">
<title>PHP</title>
<meta Name="Author" Content="Hann So">
</head>
<body>
<p>
<?php
$val = 5;
function Add($num1, $num2)
{
echo "val = ", $val, "<br />";
$sum = $num1+$num2+$val;
}
Add (3, 5);
echo "sum = ", $sum;
?>
</p>
</body>
</html>
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