Probably a stupid question, but how is best to handle a variable that gets created by an if statement in PHP?
So, the below code would work but if I changed the number 10 to 30 then the if statement would be false and $class would be undefined, which would throw an error.
What is the best way to handle this? Should I just define $class as null before my if statement?
if( 10 < 20 ) {
$class = 'less';
}
echo '<div class="number ' . $class . '">10</div>';
You can use a ternary operation here combined with empty():
if( 10 < 20 ) {
$class = 'less';
}
echo '<div class="number ' . (!empty($class) ? $class : '') . '">10</div>';
Note that whilst it's preferred to check if something exists before using it, your current code is fine. PHP will throw a notice about usage of undefined index, but it wouldn't fatal error.
However, I'd still recommend checking using empty() - much better to have perfect code that PHP won't throw errors/notices for.
Handle Like this. Yes You Should to define $class as null before if statement..
$class = "";
if( 10 < 20 ) {
$class = 'less';
}
echo '<div class="number ' . $class . '">10</div>';
You can use null-coalescing operator with parentheses to avoid undefined variable error:
if( 10 < 20 ) {
$class = 'less';
}
echo '<div class="number ' . ($class ?? '') . '">10</div>';
$class ?? '' is a short-form syntax for (isset($class) ? $class : '').
This is neither bound to PHP, nor to if alone. When a language lets you create variables "on the fly" it is merely an optional feature, not something that will take care for the overall logic.
Create your variables always on that level where you use them. In doubt, do it initially.
$class=""before if statement