How to call the c library created by shc

I have written a shell script called square, which prints the square of the input number, eg.

> square 4
16

There is a program called shc which compiles the shell scirpt and create a executable file and a c library file, namely square.x and square.x.c repectively.

If I would like to include square.x.c in another c script, such that the c script can use this square function. Then, how can I call the function in the c script?
Should I use square 4 or square(4) ?

PS: Perhaps, square can be done by common c function, but actually this is an example, I just want to know how to call the shc-compiled function in c script.

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