how-to-c/howto.md

1. Declare functions in a header file using ifndef macros to prevent multiple includes:

/* example.h file */
#ifndef EXAMPLE_H
#define EXAMPLE_H

void example(void);

#endif

Do this for each file. In this example another-example.h, third-example.h.

2. Create implementation / definition of that function:

/* example.c file */
void example(void)
{
    /* do something */
}

Do this for each file. In this example another-example.c, third-example.c.

3. Compile to object file: clang -c example.c another-example.c third-example.c. You can also do clang -c *.c.

To create archive (static library): llvm-ar r outputname.a example.c another-example.c third-example.c

To create shared object (dynamic library): ld.lld --shared -o outputname.so example.c another-example.c third-example.c

Use either with your main:

Archive: clang main.c outputname.a

---

Shared object: clang main.c outputname.so

On Linux also set correct LD_LIBRARY_PATH with export LD_LIBRARY_PATH=/path/to/outputname.so