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I was working on some code made by someone else and came across in if statement that looks like this IF($res === true){ do_something();}

This code is called many times and seems to be working. What is it doing?

I know one equals is assignment and two is comparison. What does the three equals sign operator do?

LinkReincarnate
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3 Answers3

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The easiest way to see it, is that == checks equality and === checks identicality. Equality will check the value, but identicality will check the variable type too.

Examples:

var_dump('true' == true); // bool(true)
var_dump('true' === true); // bool(false)
ollieread
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    Your examples are only going to add to the confusion for someone already having difficulty with this subject. Any non-empty string is boolean true but to use 'true' as the example string is just muddying the water. – Shazbot Dec 18 '13 at 02:00
  • Since we're explaining the difference between something being equal and something being identical, using a string called true fits perfectly. Using something other than true would just serve to confuse a user even more as they're not even remotely similar. – ollieread Dec 18 '13 at 11:42
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This is the "identical" operator. They'll need to be exactly the same to pass the condition.

The 3 different equals

Community
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James Binford
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Three === means that result has to be identical. Worded it wrong first time :)

I am Cavic
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  • I don't understand why did someone down vote this? its correct. 3 = signs means that it has to be IDENTICAL. and that is what I wrote I don't see the problem – I am Cavic Dec 18 '13 at 01:57
  • PHP doesn't have 'datatype' nor is it an object comparison, it's actually variable type. It will work with objects, somewhat. – ollieread Dec 18 '13 at 01:57
  • OK maybe I didn't word it correctly but I was trying to say exact same thing that you said it needs to be IDENTICAL. – I am Cavic Dec 18 '13 at 01:58
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    It was just to get you to change the definition, confusion can be caused by incorrect definition. – ollieread Dec 18 '13 at 01:59
  • I can appreciate that :).. Good choice ! :) – I am Cavic Dec 18 '13 at 02:00