CODEWITHSUNDEEP
phpif-statement
veilig
veilig

Reputation: 5135

can this conditional logic work in PHP?

I came across some code today where a string is compared to two values at the same time. I've never seen this before - will this work? Can someone explain it to me?

$foo = 'date';

if ($foo == ('date' || 'datetime')) {
  echo "Hello world";
}

Upvotes: 0

Views: 69

Answers (4)

GolezTrol
GolezTrol

Reputation: 116110

That won't work. Write if ($foo == 'date' || $foo == 'datetime').

Not only won't || work for selecting from a set, but also you use used a single =, which is for assignment rather than comparison.

In this case, the constant strings are compared using the boolean or operator. To do that, they are both converted to boolean. Since they are non-empty strings, they evaluate to true. true or true returns true, which is assigned to $foo which is compared to $foo. That comparison will always be true if $foo is 'date' or 'datetime' or about any other non-empty string.

So, whatever the previous value of $foo was, or even if it wasn't assigned at all, the if-expression always evaluates to true, so you always get the echo, and $foo will always be true afterwards.

Upvotes: 3

Joseph Silber
Joseph Silber

Reputation: 219938

This'll not work. ('date' || 'datetime') always evaluates to true.

Use this instead:

$foo = 'date';

if ($foo == 'date' || $foo == 'datetime') {
  echo "Hello world";
}

Upvotes: 3

Madara's Ghost
Madara's Ghost

Reputation: 174957

No. the || or OR operators only work with Booleans. you'll need this condition:

if ($foo == 'date' || $foo == 'datetime') { ... }

But what if you have 10 possible values? You'll need one for each? yes and no.

Another possibility is to insert all the possible values into an array and check whether your value is possible by comparing it to that array, using in_array():

$possible_values = array('date', 'datetime');
if (in_array($foo, $possible_values)) { ... }

Upvotes: 0

David Thomas
David Thomas

Reputation: 253318

You could try the following:

$haystack = array("date","datetime");
$needle = "date";

if (in_array($needle,$haystack)) {
    // do something
}

Upvotes: 1

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