How many max constants can i define in PHP?

My site is having around 100+ constants defined and this can potentially reach 200.

I'm using define() for defining constan开发者_如何转开发t.

Will this cause a performance hit ? How many max constants can i define in PHP ?

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PHP uses hundreds of constants itself, so no problem, you can go for as many as u like.

Just put this and see how many constants php uses itself:

$consts = get_defined_constants();
print_r($consts);

Result for me in a page only containing those lines, it showed a total of

990

constants being used with default settings and extensions loaded

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There is no issue with hundreds of constants. I think constants are only limited by memory so you can potentially have many millions if desired.

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Basically, you can have as many as memory allows. Hashtable implementation in PHP will ensure they are accessed efficiently. There are limits due to counters being 32-bit or 64-bit integers, but you will run out of memory long before that will become an issue :)