The following two if
s produced different results(first if
echos hi, second does not), why? why didn't the variable assignment on $t
work? is this due to $t
's local scope inside the if
conditional?
if(isset($_REQUEST["test"]) && $t=trim($_REQUEST["test"]) && !empty($t)){
echo 'hi'
}
if(isset($_REQUEST["test"]) && $t=trim($_REQUEST["test"])){
if(!empty($t))echo 'hi'
}
&&
has a higher precedence than =
, hence the first expression is evaluated as:
isset($_REQUEST['test']) && $t = (trim($_REQUEST['test']) && !empty($t))
Since !empty($t)
is evaluated before anything is assigned to $t
, the expression is false
. You could fix this by explicitly setting parentheses, or by using a less awkward way to write it:
if (isset($_REQUEST['test']) && trim($_REQUEST['test'])) {
echo 'hi';
}
trim($_REQUEST['test'])
will evaluate to true
or false
just by itself, no empty
necessary. If you actually need the trim
med value later, you can save it like so:
if (isset($_REQUEST['test']) && ($t = trim($_REQUEST['test']))) {
echo 'hi';
}
If you make minor modification like this in your code:
if(isset($_REQUEST["test"]) && ($t=trim($_REQUEST["test"])) && !empty($t)){
echo '1: hi<br/>';
}
if(isset($_REQUEST["test"]) && $t=trim($_REQUEST["test"])){
if(!empty($t))
echo '2: hi<br/>';
}
Then both 1: hi
and 2: hi
will be printed. Difference is parenthesis around first $t assignment.
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