This question already has answers here:
PHP conditionals, brackets needed?
(7 answers)
Closed 6 years ago.
Usually I made the if/else condition like this:
if(empty($data['key']))
{
$err = "empty . $key ";
}
but I saw that there is the ternary operator.
I really don't understand how this works.. Someone could show me an example? How can I convert this condition in the ternary logic?
I'm not sure what you're trying to do with your code.
You check if its empty, and then try to set $err to a value by concentrating an empty value.
Perhaps this is more likely what you want.
// Ternary operator
$err = empty($data['key']) ? "empty key" : '';
# -----------IF-----------------THEN ---- ELSE
// Ternary operator (nesting) (not recommended)
// Changing empty() to isset() you must rewrite the entire logic structure.
$err = empty($data) ? 'empty' : is_numeric($data) ? $data : 'not numeric';
# ---------IF--------- THEN -------ELSEIF-----------THEN-----ELSE
// Null Coalescing operator ?? available in PHP 7.
$err = $data['key'] ?? 'empty value';
# ---- IF ISSET USE --- ELSE value
// Nesting
$err = $data['key'] ?? $_SESSION['key'] ?? $_COOKIE['key'] ?? 'no key';
# IF ISSET USE -- IF ISSET USE ------ IF ISSET USE ------ELSE
Related
This question already has answers here:
How to replace "if" statement with a ternary operator ( ? : )?
(16 answers)
Closed 3 years ago.
$n = isset($_GET["n"]) ? $_GET['n'] : '';
I find this "method" to avoid errors before insert stuff in the input type.. and it works.. but I would like a detailed explanation of this line. Thank you!
This is called the ternary operator shorthand of if...else
(condition) ? true : false
There is a condition which has been checked on left, if its true the statement after the ? will be execute else the statement after the : will execute.
It's called Ternary operator
The ternary operator is a shorthand for the if {} else {} structure. Instead of writing this:
if ($condition) {
$result = 'foo'
} else {
$result = 'bar'
}
You can write this:
$result = $condition ? 'foo' : 'bar';
If this $condition evaluates to true, the lefthand operand will be assigned to $result. If the condition evaluates to false, the righthand will be used.
In your case
If the value of $_GET["n"] isset then it'll take $_GET["n"] value.
if the value is not set then it'll take ('') value.
$n = isset($_GET["n"]) ? $_GET['n'] : '';
This question already has answers here:
What are the PHP operators "?" and ":" called and what do they do?
(10 answers)
How to check if $data variable is set with Codeigniter?
(6 answers)
Closed 4 years ago.
Hey I'm new to php and codeigniter. I know codeigniter has an isset function.
what does the following code mean? Can someone please help
<?php echo isset($error) ? $error : ''; ?>
isset is a php function, you can use it without CodeIgnitor, but it basically checks to see if the variable has been set yet.
$someVariable = 'This variable has been set';
var_dump(isset($someVariable)); // True
var_dump(isset($anotherVariable)); // False
the ? and : parts tell PHP what to do. It's called a ternary operator, and can be thought as as a short if statement:
echo isset($someVariable) ? 'set' : 'not set';
is the same as:
if (isset($someVariable)) {
echo 'set';
} else {
echo 'not set';
}
http://php.net/manual/en/function.isset.php
http://php.net/manual/en/language.operators.comparison.php#language.operators.comparison.ternary
This question already has answers here:
What is ?: in PHP 5.3? [duplicate]
(3 answers)
Closed 8 years ago.
So I'm using the following php code to set variables that are received from a POST method, but I'm interested in how it works.
$var1 = isset($_REQUEST['var1']) ? $_REQUEST['var1'] : 'default';
I understand what it does, but I don't understand the syntax.
Thanks for the help :)
? is just a short and optimised notation of doing this:
if (isset($_REQUEST["var1"])) // If the element "var1" exists in the $_REQUEST array
$var1 = $_REQUEST["var1"]; // take the value of it
else
$var1 = "default"; // if it doesn't exist, use a default value
Note that you might want to use the $_POST array instead of the $_REQUEST array.
This is a short hand IF statement and from that you are assigning a value to $var1
The syntax is :
$var = (CONDITION) ? (VALUE IF TRUE) : (VALUE IF FALSE);
You probably mean ternary operator
Syntax it's same like
if(isset($_REQUEST('var1') ) {
$var1 = ? $_REQUEST('var1')
}else {
$var1 =: 'default';
}
It's the synatx of the ternary operator. It's shorthand for if/else. Please read PHP Manaul
This is a 'ternary operator', what it says is:-
If var1 is set as a post variable then set var1 to that value, otherwise setvar1 to be the string 'default'. Using traditional syntax it would be:-
if (isset($_REQUEST('var1')) { $var1 = $_REQUEST('var1'); } else { $var1 = 'default'; }
its a short way of doing an if. if you are expecting a post variable its must better to use _POST rather than request.
the "?" says if the isset($_REQUEST) is true, then do the everything between the ? and : otherwise do everything between the : and the ;
This question already has answers here:
Stacking Multiple Ternary Operators in PHP
(11 answers)
Closed 2 years ago.
I've been trying to use isset() in nested form like below:
isset($_POST['selectedTemplate'])?$_POST['selectedTemplate']:isset($_GET['selectedTemplate'])?$_GET['selectedTemplate']:0
But seems I'm missing something. Can anyone assist me how to do it?
Wrap it in parentheses:
$selectedTemplate = isset($_POST['selectedTemplate'])
? $_POST['selectedTemplate']
: (
isset($_GET['selectedTemplate'])
? $_GET['selectedTemplate']
: 0
);
Or even better, use a proper if/else statement (for maintainability):
$selectTemplate = 0;
if (isset($_POST['selectedTemplate'])) {
$selectTemplate = $_POST['selectedTemplate'];
} elseif (isset($_GET['selectedTemplate'])) {
$selectTemplate = $_GET['selectedTemplate'];
}
However, as others have pointed out: it would simply be easier for you to use $_REQUEST:
$selectedTemplate = isset($_REQUEST['selectedTemplate'])
? $_REQUEST['selectedTemplate']
: 0;
As of PHP 7 we can use Null coalescing operator
$selectedTemplate = $_POST['selectedTemplate'] ?? $_GET['selectedTemplate'] ?? 0;
A little investigate here, and I guess, I've found real answer :)
Example code:
<?php
$test = array();
$test['a'] = "value";
var_dump(
isset($test['a'])
? $test['a']
: isset($test['b'])
? $test['b']
: "default"
);
Be attentive to round brackets, that I've put.
I guess, you're waiting to get similar behavior:
var_dump(
isset($test['a'])
? $test['a']
: (isset($test['b']) // <-- here
? $test['b']
: "default") // <-- and here
);
But! Real behavior looks like this:
var_dump(
(isset($test['a']) // <-- here
? $test['a']
: isset($test['b'])) // <-- and here
? $test['b']
: "default"
);
General mistake was, that you've missed notice: Undefined index.
Online shell.
It's simpler to read if we write ternary in the following manner:
$myvar = ($x == $y)
?(($x == $z)?'both':'foo')
:(($x == $z)?'bar':'none');
But ternary operators are short, effective ways to write simple if statements. They are not built for nesting. :)
You might have an easier time simply using the $_REQUEST variables:
"$_REQUEST is an associative array that by default contains the contents of $_GET, $_POST and $_COOKIE."
http://us2.php.net/manual/en/reserved.variables.request.php
I believe this will work:
$test = array();
$test['a'] = 123;
$test['b'] = NULL;
$var = (isset($test['a']) ? $test['a'] : (!isnull($test['b']) ? $test['b'] : "default"));
echo $var;
Instead of the ternary with the ambiguous precedence, you could just use $_REQUEST instead of the fiddly $_GET and $_POST probing:
isset($_REQUEST['selectedTemplate']) ? $_REQUEST['selectedTemplate'] : 0
This is precisely what it is for.
What's the equivalent of the following (based in JS style) in PHP:
echo $post['story'] || $post['message'] || $post['name'];
So if story exists then post that; or if message exist post that, etc...
It would be (PHP 5.3+):
echo $post['story'] ?: $post['message'] ?: $post['name'];
And for PHP 7:
echo $post['story'] ?? $post['message'] ?? $post['name'];
There is a one-liner for that, but it's not exactly shorter:
echo current(array_filter(array($post['story'], $post['message'], $post['name'])));
array_filter would return you all non-null entries from the list of alternatives. And current just gets the first entry from the filtered list.
Since both or and || do not return one of their operands that's not possible.
You could write a simple function for it though:
function firstset() {
$args = func_get_args();
foreach($args as $arg) {
if($arg) return $arg;
}
return $args[-1];
}
As of PHP 7, you can use the null coalescing operator:
The null coalescing operator (??) has been added as syntactic sugar
for the common case of needing to use a ternary in conjunction with
isset(). It returns its first operand if it exists and is not NULL;
otherwise it returns its second operand.
// Coalescing can be chained: this will return the first
// defined value out of $_GET['user'], $_POST['user'], and
// 'nobody'.
$username = $_GET['user'] ?? $_POST['user'] ?? 'nobody';
Building on Adam's answer, you could use the error control operator to help suppress the errors generated when the variables aren't set.
echo #$post['story'] ?: #$post['message'] ?: #$post['name'];
http://php.net/manual/en/language.operators.errorcontrol.php
You can try it
<?php
echo array_shift(array_values(array_filter($post)));
?>
That syntax would echo 1 if any of these are set and not false, and 0 if not.
Here's a one line way of doing this which works and which can be extended for any number of options:
echo isset($post['story']) ? $post['story'] : isset($post['message']) ? $post['message'] : $post['name'];
... pretty ugly though. Edit: Mario's is better than mine since it respects your chosen arbitrary order like this does, but unlike this, it doesn't keep getting uglier with each new option you add.
Because variety is the spice of life:
echo key(array_intersect(array_flip($post), array('story', 'message', 'name')));