What's Purpose of ===

[jimmy_B]

Hi Friends.

Can anyone tell me for which purpose in PHP === is used.
Generally we use == to compare something but for which purpose === is used ?

If possible explain it with example 🙂

[Roger_Ramjet]

comparison operators

As it tells you there, the === means that the two vars are not only equal, but also of the same data type. PHP has dynamic type conversion and so will evaluate a string '4' as equal to integer 4 when using ==. This is not always what we want so we have the === to ensure that the two vars/constants are exactly equal at a binary level, ie the same data type.

[NogDog]

Just to amplify: a common need for the === and !== operators is to handle the difference between a boolean false returned from a function when it fails as opposed to a valid result of a zero or an empty string. For example, the function strpos() will return the integer 0 if the string being searched for starts at the first character in the searched string (as numbering begins with zero), and will return boolean false if it cannot find a match. Therefore, those two return values (zero or false) have different meanings, but you can only tell the difference in your code if you use the === or !== operators:

if(strpos("test string", "test"))
{
   echo "found it #1"; // will not print, as strpos() will evaluate to 0 and be treated as false 
}
if(strpos("test string", "test") != FALSE)
{
   echo "found it #2"; // will not print, as strpos() will evaluate to 0 and be treated as false 
}
if(strpos("test string", "test") !== FALSE)
{
   echo "found it #3"; // this WILL print, because zero is not identical to false 
}