# When I see a function or type name, how do I know where to find the interface definition if I do not know what header it is imported with?

**URL:** <https://forums.jcsda.org/t/when-i-see-a-function-or-type-name-how-do-i-know-where-to-find-the-interface-definition-if-i-do-not-know-what-header-it-is-imported-with/142>\
**Category:** Academy\
**Created:** [August 31, 2021, 7:00pm UTC](https://forums.jcsda.org/t/when-i-see-a-function-or-type-name-how-do-i-know-where-to-find-the-interface-definition-if-i-do-not-know-what-header-it-is-imported-with/142 "2021-08-31T19:00:55Z")\
**Posts on this page:** 1\
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**Author:** ![kshan](https://yyz1.discourse-cdn.com/flex031/user_avatar/forums.jcsda.org/kshan/32/86_2.png) [@kshan](https://forums.jcsda.org/u/kshan)\
**Post date:** [August 31, 2021, 7:00pm UTC](https://forums.jcsda.org/t/when-i-see-a-function-or-type-name-how-do-i-know-where-to-find-the-interface-definition-if-i-do-not-know-what-header-it-is-imported-with/142/1 "2021-08-31T19:00:55Z")

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More generally, how does one learn about any language intrinsics or standard library functions? A lot of research now is made much simpler with searches. I’ve learned nearly everything by opening a bunch of UFO codes to figure what others are doing; followed by [cplusplus.com](http://cplusplus.com) and other online resources.

Doxygen can help with that [OOPS: Main Page](http://data.jcsda.org/doxygen/Release/1.1.0/oops/index.html) - but more generally look for #include statements - these are include files that define the C++ interfaces.