php see if undefined
if (isset($variable)) { /* do something */ };php see if undefined
if (isset($variable)) { /* do something */ };isset in php
/**
* Returns a bool (true or false)
*/
isset($x);
/**
* Examples
*/
$x = 'myValue';
if(isset($x)){
echo 'x is set';
}
/**
* this will echo out 'x is set'
*/
$x = null;
if(isset($x)){
echo 'x is set';
}
/**
* This will NOT echo out 'x is set'
*/
if(isset($y)){
echo 'y is set';
}
/**
* This will NOT echo out 'y is set'
*/isset
<?php
if (isset($_POST['name'])) $name = $_POST['name'];
else $name = '(enter your name)';
echo <<<_END
<html>
<head>
<title>Test</title>
</head>
<body>
Your name is $name<br />
<form method = 'post' action = 'count.php'>
What's your name?
<input type='text' name='name' />
<input type='submit' />
</form>
</body>
</html>
_END
?>isset
<?php
$a = "3.1416";
if (isset($a)) // la variable $a está definida
unset($a); //ahora ya no está definida
?>Copyright © 2021 Codeinu
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