Building a multi-file program

Let's say there are three files: mainfil.cpp, subfunc.cpp, and sub.h that is included by both mainfil and subfunc.

Using Unix/Linux:

Method 1: step 1: individually compile each .cpp file:
g++ -c mainfil.cpp
g++ -c subfunc.cpp
The -c option tells to compile only, not to try to create an executable file. You could combine both in one command:
g++ -c mainfil.cpp subfunc.cpp
Either way, .o files are created: mainfil.o and subfunc.o.

Then step 2: link the .o files together into an executable file:

g++ mainfil.o subfunc.o
This creates a.out by default. To create an executable with a different name:
g++ -o prog1 mainfil.o subfunc.o
This creates an executable file called prog1.

Method 2:
With many files of many dependencies, individually compiling becomes a logistic nightmare of making sure that modifed source is recompiled and files that depend on modifed .h files are recompiled and everything is linked into a program executable. So there's a better solution: use the make utility. You specify in a file called Makefile the dependencies among the files and how to compile the files. Then after changes to the source files, you only have to give the make command; it compiles what's been modified and links what needs to be linked.

Using make. Create a file called Makefile (capital M) in the directory with the files. Its format is:
‹tab› how_to_recompile_it

There must be a tab after the filename and at the start of the compile line.
Here's the Makefile for our example:

proj1:  mainfil.o subfunc.o
        g++ -o proj1 mainfil.o subfunc.o
mainfil.o:     mainfil.cpp sub.h
        g++ -c mainfil.cpp
subfunc.o:     subfunc.cpp sub.h
        g++ -c subfunc.cpp
Makefiles pay for themselves very quickly.

Using Dev-C++:

New Project. Console Application. Give it a name and save to disk (as .dev).
each New file will be added to current project.
and/or Add existing source files to project: Project | Add to project... each .cpp file (NOT .h files)
Compile and Run project.

Using DJGPP rhide:

rhide is "project-oriented" in that it thinks all the files loaded into it are part of one program so you only have to load all the .cpp files into rhide and then Run (Ctrl-F9). This will compile them all and link them together into one executable. For the programs we're doing in this class that's easy enough. But for a program made up of many source files, a Project can be created, Add Item each .cpp file to it (don't Add the .h files). Then Run will load and compile the necessary files.

Using VC++:

in File menu,
select New,
then Projects,
Win32 Console Application,
give it a name and location.
then Empty Project.
then Project menu,
Add to Project,
and choose the .cpp files (not .h files).
A former student wrote this. I can't remember who, though.

Here's a setup that I used with Visual c++ version 5.0 that should work with 6.0. The key is to select a win32 console application under project instead of the default which assumes you want to use MFC (wonderful Microsoft). Here's the setup:
NEW -> workspace -> CMIS240 (for example)
NEW -> project -> win32 Console Application
Projectname assignment1
ALSO Select Add to current workspace
Next under your new project
select NEW FILE and use the C++ source file and give it a file name.

Using Turbo 3.0:

Project menu, Open project, create some .PRJ file in the directory where the files are. Add Item for each .cpp file (i.e. mainfil.cpp and subfunc.cpp) but NOT for the .h files. Compiling will compile each modified file and link together into an executable.

Using Borland 4.5:

Maybe Borland 5 is similar? Thanks to Matt Vogel for researching this.
  1. Project menu, choose New project. In pop-up window, give name for the project. Use name of file containing main(). Select EasyWin[.exe] as the Target Type.
  2. In the Project window, right click on the top file[.exe]. Add node for each .cpp that makes up the project.
  3. Delete the two extra files that the compiler supplies (.rc and .def). If you delete them the compiler does not ask for them. Delete by right mouse button, choose Delete node.
  4. To compile the project make sure to choose the Make all option from the Project menu at the top. If you click on the project.exe in the project window the compiler will attempt to compile the project and give you errors.
  5. Once the project has been complied and built with 0 errors do not run the project from inside the compiler. It will give you an error. Instead find the .exe file that the compiler made using Windows Explorer and double click on it to run the program. You can also run the program from the DOS prompt.