Compiler Input and Output

The compiler takes source files with extensions like .f and .for (Fortran) and .c, .cpp, and .cxx (C/C++) and produces corresponding .o (Object) files. For example to compile C++:-

g++ -c Animal.cpp

would produce the file Animal.o from Animal.cpp. The corresponding C and Fortran commands are:-

gcc -c Animal.c

g77 -c Animal.for

All three commands g++, gcc and g77 act as an interface to a common GNU compiler.

You cannot run the output from the compiler because:-

• It has not been bound to a specific area in memory.

• Normally it will be incomplete and will refer to other, independently compiled functions, either that form part of the application or are provided as part of the operating environment e.g. I/O.

So compiler output has to be passed to a second stage: the linker, see section 6.1.4