What's the difference between equal and identical comparison operators in PHP?

Question

Possible Duplicate:
How do the equality (== double equals) and identity (=== triple equals) comparison operators differ?

I know the basic difference between == and === , but can some experienced coders tell me some practical examples for both cases?

See http://stackoverflow.com/questions/3641819/php-not-equal-to-and/3641837#3641837 (compares `!=` and `!==` but you get the idea) — BoltClock, Jan 19 '11 at 07:24
http://www.php.net/manual/en/types.comparisons.php gives a great overview! — Paul, Jan 19 '11 at 14:14

score 23 · Accepted Answer · answered Jan 19 '11 at 07:27

== checks if the values of the two operands are equal or not. === checks the values as well as the type of the two operands.

if("1" == 1)
   echo "true";
else
   echo "false";

The above would output true.

if("1" === 1)
   echo "true";
else
   echo "false";

The above would output false.

if("1" === (string)1)
   echo "true";
else
   echo "false";

The above would output true.

score 1 · Answer 2 · answered Jan 19 '11 at 07:28

1

Easiest way to display it is with using strings. Two examples:

echo ("007" === "7" ? "EQUAL!" : "not equal"); 
echo ("007" == "7" ? "EQUAL!" : "not equal");

answered Jan 19 '11 at 07:28

Bjoern

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score 1 · Answer 3 · answered Jan 19 '11 at 07:32

In addition to @DavidT.'s example, a more practical example is the following:

$foo = "Goo";
$bar = "Good Morning";
if (strpos($bar,$foo))
  echo "Won't be seen, returns false because the result is in fact 0";
if (strpos($bar,$foo) !== false)
  echo "True, though 0 is returned it IS NOT false)";

What's the difference between equal and identical comparison operators in PHP?

3 Answers3