Laboratory Exercises, C++ Programming

4 The GNU Compiler Collection and C++
• Define the class in a file myclass.h:
#ifndef MYCLASS_H // include guard
#define MYCLASS_H
// #include necessary headers here
class MyClass {
public:
MyClass(int x);
// ...
private:
// ...
};
#endif
• Define the member functions in a file myclass.cc:
#include "myclass.h"
// #include other necessary headers
MyClass::MyClass(int x) { ... }
// ...
• Define the main function in a file test.cc (the file name is arbitrary):
#include "myclass.h"
int main() {
MyClass m(5);
// ...
}
The include guard is necessary to prevent multiple definitions of names. Do not write function
definitions in a header (except for inline functions and template functions).
The g++ command line looks like this:
g++ [options] [-o outfile] infile1 [infile2 ...]
All the files in a program can be compiled and linked with one command (the -o option specifies
the name of the executable file; if this is omitted the executable is named a.out):
g++ -o test test.cc myclass.cc
To execute the program, just enter its name:
./test
However, it is more common that files are compiled separately and then linked:
g++ -c myclass.cc
g++ -c test.cc
g++ -o test test.o myclass.o
The -c option directs the driver to stop before the linking phase and produce an object file, named
as the source file but with the extension .o instead of .cc.
The driver can be interrupted also at other stages, using the -S or -E options. The -S option
stops the driver after assembly code has been generated and produces an assembly code file