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Is it possible to identify and distinguish between types with Fortran Select Type?

It can Select Type

distinguish between Integer(Int8)

, Integer(Int16)

, Integer(Int32)

and Integer(Int64)

?

Also, can Select Type

an integer type be identified regardless of the number of bits it uses?

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2 answers


Yes, you can write something like the following. Here I am using real view constants from the built-in module iso_fortran_env

.

SELECT TYPE(areal)
TYPE is (REAL(real32))
   WRITE(*,*) '... real32'
TYPE is (REAL(real64))
   WRITE(*,*) '... real64'
CLASS default
   WRITE(*,*) '... default'
END SELECT

Please note that you cannot write



SELECT TYPE(areal)
TYPE is (REAL(real32))
   WRITE(*,*) '... real32'
TYPE is (REAL(real64))
   WRITE(*,*) '... real64'
TYPE is (REAL)
    WRITE(*,*) '... real'
CLASS default
   WRITE(*,*) '... default'
END SELECT

In this case, the real default type (probably real32

for most modern compilers) will correspond to two statements of type guard, as well as the error that the compiler should receive.

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Different whole types represent different internal types. So yes, it does select type

allocate integers of different types.



I don't know of any way to ignore the view (i.e. not just the number of bytes, in theory). You must use a separate section type is

for each type.

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