Most publicly available OS/2 programs come with binaries (since there is currently only one OS/2 architecture). If you are porting source code from another system (for example, Unix), you will first need to acquire a compiler. See section 1 for information on compilers; in particular, note that the GNU C compiler is available.
You should realize that many publicly available programs have already been ported to OS/2. Check the many FTP sites carrying OS/2 programs before you reinvent any wheels (the OS/2 User's FAQ contains information on FTP site).
Most Unix applications (through the use of emx/gcc) port with extreme ease; DOS and Windows applications are a tougher problem, and require many changes before they can be recompiled as a native OS/2 program.
(It is interesting to note that MicroSoft C v6.0 will compile bound OS/2
programs, which will run under DOS and OS/2 without modification.)
Related Information:
How can I port my DOS program
to OS/2?
How can I port my Windows program
to OS/2?