($DAO->get_num_rows() == 1) ? echo("is") : echo("are");
This dose not seem to be working for me as intended, I get an error "Unexpected T_ECHO". I am expecting it to echo either 'is' or 'are'.
I have tried it without the brackets around the conditional. Am I just not able to use a ternary operator in this way?
The $DAO->get_num_rows() returns an integer value.
A Ternary is not a good solution for what you want. It will not be readable in your code, and there are much better solutions available.
Why not use an array lookup "map" or "dictionary", like so:
$vocations = array(
1 => "Sorcerer",
2 => "Druid",
3 => "Paladin",
...
);
echo $vocations[$result->vocation];
A ternary for this application would end up looking like this:
echo($result->group_id == 1 ? "Player" : ($result->group_id == 2 ? "Gamemaster" : ($result->group_id == 3 ? "God" : "unknown")));
Why is this bad? Because - as a single long line, you would get no valid debugging information if something were to go wrong here, the length makes it difficult to read, plus the nesting of the multiple ternaries just feels odd.
A Standard Ternary is simple, easy to read, and would look like this:
$value = ($condition) ? 'Truthy Value' : 'Falsey Value';
or
echo ($some_condition) ? 'The condition is true!' : 'The condition is false.';
A ternary is really just a convenient / shorter way to write a simple if else statement. The above sample ternary is the same as:
if ($some_condition) {
echo 'The condition is true!';
} else {
echo 'The condition is false!';
}
However, a ternary for a complex logic quickly becomes unreadable, and is no longer worth the brevity.
echo($result->group_id == 1 ? "Player" : ($result->group_id == 2 ? "Gamemaster" : ($result->group_id == 3 ? "God" : "unknown")));
Even with some attentive formatting to spread it over multiple lines, it's not very clear:
echo($result->group_id == 1
? "Player"
: ($result->group_id == 2
? "Gamemaster"
: ($result->group_id == 3
? "God"
: "unknown")));
You need to bracket the ternary conditionals:
<?php
for ($a=0; $a < 7; $a++) {
echo (
$a == 1 ? 'one' :
($a == 2 ? 'two' :
($a == 3 ? 'three' :
($a == 5 ? 'four' : 'other'))));
echo "n";
// prints 'four'
}
exit;
?>
returns:
other
one
two
three
other
four
other
as you'd expect.
See the note at the bottom of "Ternary operators" at PHP Ternary operator help.
The expressions are being evaluated left to right. So you are actually getting:
echo (
((($a == 1 ? 'one' : $a == 2)
? 'two' : $a == 3) ? 'three' :
$a == 5) ? 'four' : 'other');
So for $a=2, you get:
echo (
((($a==2) ? 'two' : $a == 3) ? 'three' :
$a == 5) ? 'four' : 'other');
and then
echo (
((true ? 'two' : $a == 3) ? 'three' :
$a == 5) ? 'four' : 'other');
and then
echo (
('two' ? 'three' : $a == 5) ? 'four' : 'other');
and then
echo (
'three' ? 'four' : 'other');
and so echo 'four'.
Remember that PHP is dynamically typed and treats any non-zero non-null values as TRUE.
Don't use the ternary operator then, it requires a third argument. You would need to reassign max to max if you don't want it to change (max = (max < b) ? b : max).
An if-statement is much more clear:
if (max < b) max = b;
And if you need it to be an expression, you can (ab)use the short-circuit-evaluation of AND:
(max < b) && (max = b)
Btw, if you want to avoid repeating variable names (or expressions?), you could use the maximum function:
max = Math.max(max, b);
Try:
final Double verwachtMin = avg != null ? new Double(Math.max(min, avg - 3 * sd)) : min;
or
final Double verwachtMin = avg != null ? Double.valueOf(Math.max(min, avg - 3 * sd)) : min;
The types of the alternate sides of the ternary operator were double and Double, which means that the Double gets unboxed to double, and then on assignment we have a boxing from double to Double. If the value of min is null then the unboxing NPEs.
The Ternary operator is not identical to an if-then. You should have written it
It returns the value in the 2nd or 3rd position. It does NOT execute the statement in the 2nd or 3rd position.