PHP/Language Basics/Variable Set Unset
Содержание
IsSet variable
<?
$MyVar="Hello there!";
If(IsSet($MyVar))
echo "The variable is set. Its value is $MyVar";
?>
The isset() Function
<html>
<head>
<title>Isset()</title>
</head>
<body>
<?php
$my_var = 100;
if(isset($my_var)) {
print("\$my_var is set... the value is " . $my_var);
}
print("<br/>");
print(isset($some_var) . "<br />");
$some_var = "I am set";
print(isset($some_var) . "<br />");
?>
</body>
</html>
UnSet array element
<?
$A=array(0=>"zzzz",
"a"=>"aaa",
"b"=>"bbb",
"c"=>"ccc");
Unset($A["a"]);
echo $A["a"]
?>
unset() Function
<html>
<head>
<title>Unset()</title>
</head>
<body>
<?php
$authorJ = "A";
$authorC = "B";
$jeremy = &$authorJ;
$charlie = &$authorC;
print("$authorJ <br/>");
unset($jeremy);
print($authorJ . " or " . $jeremy . "<br />");
print("$authorC <br />");
unset($charlie);
unset($authorC);
print($authorC);
?>
</body>
</html>
Unset variable
<?
$a="Hello there!";
echo $a
unset($a);
echo $a; // Error: there is no variable $a
?>