Compile Two Files:
$ CC -c Main.cc Sales_item.cc # by default generates a.exe
# some compilers generate a.out
# puts the executable in main.exe
$ CC -c main.cc Sales_item.cc -o main
More efficient way is to only compile the modified file. Thus we need to compile original files into object files.
Link Object Files:
$ CC -c main.cc # generates main.o
$ CC -c Sales_item.cc # generates Sales_item.o
$ CC main.o Sales_item.o -o main # by default generates a.exe;
# some compilers generate a.out
Linux Compile Multiple C++ Files
原文：http://www.cnblogs.com/kid551/p/4251995.html