How to edit, compile, and run your
c++ program.
An object-oriented version of C created by Bjarne
Stroustrup.
C++ has become popular because it combines traditional
C programming with OOP capability.
g++ - GNU project C++ Compiler
To
obtain extra help type:
$
man g++
To establish that your system has the correct C++
compiler
installed, at the command prompt type this:
$ g++ -v
1.
Open vi text editor associated with a file name, remember
to use the extension .cpp
$ vi programname.cpp (program.cpp will be the
name of your program. After
you type your program save it.
2.
At the shell prompt type:
$ g++ programname.cpp
to compile your program. If there are error messages generated
by the compiler such as syntax errors on your program, go back
and reopen the file. Save the file and re-compile it. If successful
it will create an executable file called a.out
3.
Run your program by typing the full path for
$ ~/a.out Note: if you do not wish by
default create the file a.out, you can
tell the compiler to create a name that
you specify for the executable file by
using the command:
$ g++
programname.cpp �o desiredname
How
to compile and execute C++ files on HP
%CC filename.cpp (compiling)
%a.out (executing)
If
you want to compile more C++ files, you can do
%CC filename1.cpp filename2.cpp(compiling)
%a.out (executing)
How
to compile and execute C++ files on IBM-UNIX
%xlC filename.C (compiling)
%a.out (executing)
where,
C++ file extension name on IBM is .C file.
If
you want to compile more C++ files, you can do
%xlC filename1.C filename2.C (compiling)
%a.out (executing)
If your system is set up correctly, this command will
launch the
compiler executable and print its version. If an error message
is printed instead, you will have to consult your documentation
to make sure the compiler is installed and set up correctly.
Create a file named hello.cpp with this content:
#include <iostream>
using namespace std;
int main()
{
cout << "Hello World!, this is my
first C++ program" << endl;
return 0;
}
Using Makefiles
make is useful when maintaining or updating groups
of
programs or other kinds of files. If a program consists of
more than one module then make
will be useful. make
uses
a makefile which lists the dependencies of a final file
upon
other files. To make a new version of the final file (or target)
make
since the last version of the target was made. The
makefile
must be in the directory with the program.
Creating
a makefile
1.
Using a text editor such as vi, create and open a file called
makefile.
2.
For every two files that must be linked together, you must
create an object file. The object file is an intermediate
compiled source file. Now, to compile and create an object
file from two source files (for example, a C/C++ header file
and a C/C++ source file),
o
Specify
the target. The target is the object file,
which must have a .o extension.
o
Use the cc
command with the -c flag as described
above to compile the two files together.
The
format in which this must be typed is:
target: files
cc source_files -c
3.
Once you've created the object files,
o
Compile
and link them together with the cc command
with the -o flag as described above.
o
Specify
the name of the target (default is a.out).
The target is the executable file.
The
format for this is much the same:
target: files
cc source_files -o target
4.
The catch is that these parts must be typed into the makefile
in reverse order: starting at the top with the executable as the
target, with the object files as targets on the lines below.
5.
Save the file as makefile and exit.
6.
To compile and link the files, and create an executable,
simply type make at the command prompt.
Example
of a makefile
Let
us consider an example where we have three files:
 |
class.h;
a header file containing a class definition.
|
|
class.C;
a source file containing the implementation of the
class. This file is linked to class.h with an include statement.
|
|
file.C; the main program. This file is linked
to file.C with an
include statement as well.
|
The
contents of the makefile should be:
executable: class.h class.o file.o
cc class.o file.o -o list
class.o: class.h class.C
cc -c class.C
file.o: class.h file.C
cc -c file.C
The
process starts from the bottom up.
1.
The object file file.o is created by linking the source
file file.C with the header file class.h. The source file is
compiled with the -c flag, which allows the object file to
be created. The header file is not compiled be cause it does
not contain source code.
2.
The object file class.o is created by linking the source
file class.C with the header file class.h. The source file
is again compiled with the -c flag, creating the object file.
The header file is not compiled.
3.
The executable file executable is created by linking the
object files class.o and file.o with the header file class.h.
The object files are compiled with the -o flag, which allows
you to specify the name of the output file.
| 
