Since isset appears to be a function (http://php.net/manual/en/function.isset.php), there might be some overhead for calling it. So I wonder if using !== null instead of isset would produce faster code while, most importantly, keeping the code's behavior exactly the same?
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Desmond Hume
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`isset` is a language construct, not a function. – Joey Jul 19 '13 at 11:09
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1They are not the same. If your variable is not set, `isset` will not produce a warning - you are effectively saying, by using this function, that this is okay. If you use `!==` then you'll get a warning if the variable is not set. – halfer Jul 19 '13 at 11:14
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deceze wrote [this article](http://kunststube.net/isset/) on `isset`, `empty`, `!$var` and all that... read it to fully understand the differences and pitfals – Elias Van Ootegem Jul 19 '13 at 11:25
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From PHP Manual:
isset — Determine if a variable is set and is not NULL
isset Returns TRUE if var exists and has value other than NULL, FALSE otherwise.
http://php.net/manual/en/function.isset.php
The function call overhead is so small you probably don't need to worry about it. Read this post: Why are PHP function calls *so* expensive?
Note that isset is not a function (it has a special opcode for it), so it's faster.
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Elliot Lings
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isset is not a function, It is a Language construct in PHP, It is much faster.
isset determines if a variable is set and is not NULL.
srain
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as above isset is to check if a variable is set and is not NULL. To make sure I usually use it as
if( isset( $var ) === TRUE )
{
// Do what you want
}
This doesn't throw any unnecessary notices in PHP
Hari Ramamurthy
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1There is no need for check TRUE. isset Returns TRUE if var exists and has value other than NULL, FALSE otherwise. – Ravi Feb 17 '16 at 06:00