module to replace common block

[feipeng]

Recently, we are upgrading our old software from F77 to F95. One issue is to replace the old common block with module. I have a question:

In the module, should every variable has the attribut "SAVE" to share the value among different procedures? Or, it's not necessary.

I have just done some experiment with and without "SAVE" attribute. The software works same. From experiment, it seems the "SAVE" attribute is not necessary. I wonder, is it the way of Fortran stardards? or it depends on the compiler.

Thanks for your hint!

Feipeng

[Steven_L_Intel1]

The Fortran standard says that module variables retain their definition as long as there is an active program unit that references that module. Theoretically, if you have a program structured like this:

module moda

integer moda_variable

end module moda

program test

call sub1

call sub2

end

subroutine sub1

use moda

moda_variable = 1

end

subroutine sub2

use moda

print *, moda_variable

end

then the variable in module moda could become undefined when sub1 returns. If the main program also did a "use moda", then this would not be an issue. In practice, most compilers, including Intel's, allocate such variables statically and they retain their values.

It doesn't hurt to use SAVE in this case. One never knows what future compilers might do.

Message Edited by Steve_Lionel on 03-10-2006 10:06 AM

[feipeng]

Thanks a lot!

Feipeng