As i see in your output log (build window), your compilation string not have -lauto (which you need to add all the time). -lauto mean including of stab library caleld libauto.a, to make all that IIxxxxxx and other references works. In other words you can just go to shell and type "gcc window.c -o window -lauto", or just add in codebench to build string -lauto. ps. What you mean by "gcc run code in main.c" ? Imho in your case main.c file just a source file, without any specific reles to compilator. Its you later choice by which compiler compile a objects/binary (by gcc, or by vbcc, or any other).