About preprocessing of FORTRAN code
You can use preprocessing to activate different code sections as needed. E.g.:
Main.F:
…
#define debug
#ifdef debug
write(*,*) "hello 1"
#else
write(*,*) "hello 2"
#endif
…
By default, the directives begin with # will be treated as comments. If you compile this file directly by ifort Main.F, you will get the following code in Main.for:
write(*,*) "hello 2"
To active the preprocess directives, you need to add the option of -fpp at compilation step. Here fpp stands for “FORTRAN preprocessor”.
ifort main.F -fpp
or if you use MS visual studio, turn on fpp:
click Project->Console properties:
After compilation, you will get the following code in main.for:
write(*,*) "hello 1"
if you want to “#define debug” at compilation step instead of hardcoding. You can:
…
#ifdef debug
write(*,*) "hello 1"
#else
write(*,*) "hello 2"
#endif
…
WIN: ifort Main.F -fpp /Ddebug or Linux: ifort Main.F -fpp -Ddebug
or manually add option “debug” in MS Visual studio as below.
After compilation, you will get the following code in main.for:
write(*,*) "hello 1"
