# Key word for undefined in PHP?

**URL:** <https://forum.kirupa.com/t/key-word-for-undefined-in-php/27870>\
**Category:** Uncategorized\
**Created:** [August 7, 2003, 12:17pm UTC](https://forum.kirupa.com/t/key-word-for-undefined-in-php/27870 "2003-08-07T12:17:24Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Johnny64](https://avatars.discourse-cdn.com/v4/letter/j/ed655f/32.png) [@Johnny64](https://forum.kirupa.com/u/Johnny64)\
**Post date:** [August 7, 2003, 12:17pm UTC](https://forum.kirupa.com/t/key-word-for-undefined-in-php/27870/1 "2003-08-07T12:17:24Z")

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Hoi

what is the key word for undefined in PHP?

:}

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**Author:** ![system](https://canada1.discourse-cdn.com/flex011/uploads/kirupa/original/3X/6/2/621e5c11736f46532526e61be85940af4230f3e5.png) [@system](https://forum.kirupa.com/u/system)\
**Post date:** [August 7, 2003, 12:20pm UTC](https://forum.kirupa.com/t/key-word-for-undefined-in-php/27870/2 "2003-08-07T12:20:47Z")

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well you have [color=blue]isset(variable)[/color] to determine if a variable is defined or not (essentially checking to see if it is undefined) is that what you need?

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**Author:** ![system](https://canada1.discourse-cdn.com/flex011/uploads/kirupa/original/3X/6/2/621e5c11736f46532526e61be85940af4230f3e5.png) [@system](https://forum.kirupa.com/u/system)\
**Post date:** [August 7, 2003, 12:27pm UTC](https://forum.kirupa.com/t/key-word-for-undefined-in-php/27870/3 "2003-08-07T12:27:51Z")

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yeah ([size=1]i thing!![/size])

does that return true or false?

:}

thanks

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<div class="post-metadata">

**Author:** ![system](https://canada1.discourse-cdn.com/flex011/uploads/kirupa/original/3X/6/2/621e5c11736f46532526e61be85940af4230f3e5.png) [@system](https://forum.kirupa.com/u/system)\
**Post date:** [August 7, 2003, 12:31pm UTC](https://forum.kirupa.com/t/key-word-for-undefined-in-php/27870/4 "2003-08-07T12:31:26Z")

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Ok never mind found it in the PHP manual

what is the PHP thing for ! in flash?

:}

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<div class="post-metadata">

**Author:** ![system](https://canada1.discourse-cdn.com/flex011/uploads/kirupa/original/3X/6/2/621e5c11736f46532526e61be85940af4230f3e5.png) [@system](https://forum.kirupa.com/u/system)\
**Post date:** [August 7, 2003, 12:33pm UTC](https://forum.kirupa.com/t/key-word-for-undefined-in-php/27870/5 "2003-08-07T12:33:12Z")

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!

😉

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<div class="post-metadata">

**Author:** ![system](https://canada1.discourse-cdn.com/flex011/uploads/kirupa/original/3X/6/2/621e5c11736f46532526e61be85940af4230f3e5.png) [@system](https://forum.kirupa.com/u/system)\
**Post date:** [August 7, 2003, 12:34pm UTC](https://forum.kirupa.com/t/key-word-for-undefined-in-php/27870/6 "2003-08-07T12:34:27Z")

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:trout:

thanks :}