how to compile code into executable and library separately

I have a program with one "Main function" file and a series of "Other files" functions being called from the main function file to do number crunching. I usually compile everything into one BIG executable. And it has been working greatly so far.

The question I have is is it possible to just compile "Other files" into a separate library file, such as DLL, JAR or whatever and only have a SMALLER executable which will link to the library which is frequently updated. The goal is whenever I update the "Other files" I just need to recompile the library, not the executable

Thanks Sam