How to create an embeddable C-API library in Go?

I am planning to write a cross-platform app that has most of its functionality shared across all platforms (Linux, OS X, Windows, iOS, Android).
These are mostly helper function (calculations, internal lists, networking etc.) so I figured it would be convenient to have those functions in a library I can compile for every platform while still being able to create custom UI for each platform individually.

Dominant languages across those platforms I mentioned are C, Objective-C, C# and Java. All these languages support calling C-API functions from a library either directly or via internal wrappers. Since I don't want to write 80% of my application's code in C/C++, I searched and found Go.

cgo seems to be the solution for my problem.<br>
My current thought is to code the core library in Go and then compile it for each platform, however, invoking go build does not create anything at all.<br>
I import "C".<br>
I have declared a func and added the //export statement before.

I read about gccgo but people keep pointing out that it is outdated and should not be used.

Maybe anyone can point out a flaw in my thoughts or help me bring this library file together. Thanks in advance.

If your aim is to build a library that can be linked into arbitrary C, Objective-C or Java programs, you are out of luck with the currently released standard tool chain. There are plans to change this in the future, but at present the Go runtime is not embeddable in other applications.

While cgo will allow you to export functions to be called from C, this is only really useful for cases when the C code you call from Go needs to call back to Go.