isset function in php
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<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
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<body>
<form action="" method="post">
<h1>ISSET Demo</h1>
<input type="submit" value="Click here" name="btn1">
</form>
</body>
</html>
<?php
if(isset($_POST['btn1']))
{
echo "button was set!";
}
?>isset in php
/**
* Returns a bool (true or false)
*/
isset($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'
*/what is isset in php
The isset() function checks whether a variable is set, which means that it has to be declared and is not NULL.
This function returns true if the variable exists and is not NULL, otherwise it returns false.php isset
<?php
$var = '';
// This will evaluate to TRUE so the text will be printed.
if (isset($var)) {
echo "This var is set so I will print.";
}
// In the next examples we'll use var_dump to output
// the return value of isset().
$a = "test";
$b = "anothertest";
var_dump(isset($a)); // TRUE
var_dump(isset($a, $b)); // TRUE
unset ($a);
var_dump(isset($a)); // FALSE
var_dump(isset($a, $b)); // FALSE
$foo = NULL;
var_dump(isset($foo)); // FALSE
?>Copyright © 2021 Codeinu
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