Is there a way to prevent using if to check if an element exists before append ing itto a string, so it does not cause an error?
e.g.
$output = "";
if($data['element'])
{
$output .= $data['element'];
}
in Javascript I can use:
var output = "";
output += data['element'] || '';
You could always use the Ternary Operator ?:
$output .= (isset($data['element'])) ? $data['element'] : '';
From the PHP Docs
The expression (expr1) ? (expr2) : (expr3) evaluates to expr2 if expr1 evaluates to TRUE, and expr3 if expr1 evaluates to FALSE.
Since PHP 5.3, it is possible to leave out the middle part of the ternary operator. Expression expr1 ?: expr3 returns expr1 if expr1 evaluates to TRUE, and expr3 otherwise.
use isset to check it.
$output = "";
if(isset($data['element']))
{
$output .= $data['element'];
}
Use the PHP Ternary Operator like this:
(isset($data['element'])) ? $output=$data['element'] : $output="";
Related
This question already has answers here:
What are the PHP operators "?" and ":" called and what do they do?
(10 answers)
Closed 9 years ago.
what is the meaning of this line? Can any body help me? I have confusion on last 2 sign :''
why without this two sign browser make error? Thanks all.
isset($_POST['but'])? $_POST['but']:'';
U use the tenary comparison operator
A ternary operator have value for true and false
($contidition) ? true : false;
Please refer php documentation about ternary operator comparison operator
In case of:
isset( $_POST['but'] ) ? $_POST['but'] : ''
What it mean is, when $_POST['but'] exist, use it, otherwise use empty string
If u use php version > 5.3 u can use something like
isset($_POST['but']) ? : ''
It's just another way to write if/else statement.
For example:
$but = isset($_POST['but'])? $_POST['but']:'';
Would be the same as:
if(isset($_POST['but'])){
$but= $_POST['but'];
}else{
$but = '';
}
If $_POST request body contains but parameter - use it, overwise use empty string.
If you are misunderstood statement ? something : anything code - it's the Ternary Operator
It's nothing but the Ternary Operator
Explanation:
If your $_POST['but'] is set , then it will assign the same value to it , else it will set a ''
A clear example here
Well it's called an ternary operator.
Example:
$value = 5;
($value > 2) ? true : false; // returns true
The expression (expr1) ? (expr2) : (expr3) evaluates to expr2 if expr1 evaluates to TRUE, and expr3 if expr1 evaluates to FALSE.
(isset($_POST['but'])) ? $_POST['but']:'';
Here if your value $_POST['but'] is set then it will return $_POST['but'] else it will return ''.
In an online tutorial I have seen the following snippet of code:
$this->data = $data ?: \Input::all();
Is this a standard ternary operator? What would happen when $data evaluates to true?
Does the following code do the same thing as the original I posted?
$this->data = $data ? null : \Input::all();
It's a ternary operator, shortcut of
$this->data = $data? $data : \Input::all();
From http://php.net/manual/en/language.operators.comparison.php
Since PHP 5.3, it is possible to leave out the middle part of the ternary operator.
Expression expr1 ?: expr3 returns expr1 if expr1 evaluates to TRUE, and expr3 otherwise.
Given the following expression:
$att['menutext'] = isset($attrib_in['i_menu_text']) ? : $this->getID();
If it evaluates to true, will $att['menutext'] be set to true or $this->getID()?
According to this reference:
Since PHP 5.3, it is possible to leave out the middle part of the
ternary operator. Expression expr1 ?: expr3 returns expr1 if
expr1 evaluates to TRUE, and expr3 otherwise.
Yes, in version 5.3+ the middle expression is optional and returns true.
$a = (true ? : 1); // $a evaluates to true.
$a = (false ? : 1); // $a evaluates to 1.
It's just the same as the following
$att['menutext'] = isset($attrib_in['i_menu_text']) ? true : $this->getID();
never tested before, but its quite easy to test:
<?php var_dump(TRUE ? : 'F'); ?>
and its says: bool(true)
This won't execute, it's invalid syntax for PHP < 5.3.
Parse error: syntax error, unexpected ':' on line X
If you want the value to be set to true, then use true:
$att['menutext'] = isset($attrib_in['i_menu_text']) ? true : $this->getID();
Or it may be more likely that you want:
$att['menutext'] = isset($attrib_in['i_menu_text']) ? $attrib_in['i_menu_text'] : $this->getID();
what does this structure mean:
$var = isset($var_1) ? $var_1 : $var_2;
I came across it and of course with other values, not $va, $var_1 and $var_2.
thanks.
This is the ternary operator, and means the same as:
if (isset($var_1)) {
$var = $var_1;
}
else {
$var = $var_2;
}
The ternary operator provides a short-hand method of creating simple if/else statements.
It has some syntax errors, correctly:
$var = isset($var_1) ? $var_1 : $var_2;
This means:
if (isset($var_1))
{
$var = $var_1;
}
else
{
$var = $var_2;
}
That means:
if(isset($var_1))
$var = $var_1;
else
$var = $var_2;
It is short syntax for that.
just for your information from the php manual i copy pasted good things to know about ternary comparision operators
The expression (expr1) ? (expr2) : (expr3) evaluates to expr2 if expr1 evaluates to TRUE, and expr3 if expr1 evaluates to FALSE.
Since PHP 5.3, it is possible to leave out the middle part of the ternary operator. Expression expr1 ?: expr3 returns expr1 if expr1 evaluates to TRUE, and expr3 otherwise.
Note: Please note that the ternary operator is a statement, and that it doesn't evaluate to a variable, but to the result of a statement. This is important to know if you want to return a variable by reference. The statement return $var == 42 ? $a : $b; in a return-by-reference function will therefore not work and a warning is issued in later PHP versions.
Note:
It is recommended that you avoid "stacking" ternary expressions. PHP's behaviour when using more than one ternary operator within a single statement is non-obvious:
Example #3 Non-obvious Ternary Behaviour
<?php
// on first glance, the following appears to output 'true'
echo (true?'true':false?'t':'f');
// however, the actual output of the above is 't'
// this is because ternary expressions are evaluated from left to right
// the following is a more obvious version of the same code as above
echo ((true ? 'true' : false) ? 't' : 'f');
// here, you can see that the first expression is evaluated to 'true', which
// in turn evaluates to (bool)true, thus returning the true branch of the
// second ternary expression.
?>
Simple question. Here is this code.
$r = rand(0,1);
$c = ($r==0)? rand(65,90) : rand(97,122);
$inputpass .= chr($c);
I understand what it does in the end result, but I'd like a better explanation on how it works, so I can use it myself. Sorry if this is a bad question.
If you're unsure of what I'm asking about, its the (function?) used here:
$c = ($r==0)? rand(65,90) : rand(97,122);
That's called a ternary operator. It's effectively the equivalent of
if ($r == 0) {
$c = rand(65, 90);
} else {
$c = rand(97, 122);
}
But it's obviously a bit more compact. Check out the docs for more info.
That simply means:
if($r==0){
$c = rand(65,90);
else{
$c = rand(97,122);
}
If the statement is true the first operation after that ? is executed, else the operation after : is executed.
Its called a ternary operator.
Its the Ternary Operator
<?php
// Example usage for: Ternary Operator
$action = (empty($_POST['action'])) ? 'default' : $_POST['action'];
// The above is identical to this if/else statement
if (empty($_POST['action'])) {
$action = 'default';
} else {
$action = $_POST['action'];
}
?>
The expression (expr1) ? (expr2) : (expr3) evaluates to expr2 if expr1 evaluates to TRUE, and expr3 if expr1 evaluates to FALSE.
Since PHP 5.3, it is possible to leave out the middle part of the ternary operator. Expression expr1 ?: expr3 returns expr1 if expr1 evaluates to TRUE, and expr3 otherwise.
It's called the ternary operator. It's similar to an if/else construct, but the difference is that an expression using the ternary operator yields a value.
That is, you can't set a variable to the result of an if/else construct:
// this doesn't work:
$c = if ($r == 0) {
rand(65, 90);
} else {
rand(97, 122);
}
You can read more about it here: http://php.net/ternary#language.operators.comparison.ternary
The ternary operator is frequently misused. There's little benefit to using it in the example you showed. Some programmers love to use compact syntactic sugar even when it's not needed. Or even when it's more clear to write out the full if/else construct.
The ternary operator can also obscure test coverage if you use a tool that measures lines of code covered by tests.