One compiler printed words: "firstsecond" lengths: 5 6 with this program: implicit none character(:),allocatable::a,b,words(:) a = 'first' b = 'second' allocate(character(max(len(a),len(b))) :: words(2)) words(1) = a words(2) = b print "(4A,2I2)",'words: "',words,'" lengths:',len(…

But here, there is no array constructor. Instead, we have two assignments to words elements 1 and 2. The array surely has all elements of the same length, 6. So the only guess that comes to my mind is that your compiler treats ‘A’ descriptor as the F2023 new ‘AT’, i.e. with auto-trimming. Edit: my …

[image] Harper: I suspect that different elements of an allocatable character array can’t have different lengths, but does the Fortran standard say so? If so, where? This is a very interesting question. Length is a type parameter, so changing the length of an individual array element would im…

[image] Harper: words: "firstsecond" lengths: 5 6 If the programmer wants this behavior, that is different array elements can have different lengths, or even different allocation status, then in fortran it is done with a derived type array where each element has an allocatable component. An e…

I have always found the requirement to add the allocatable keyword to deferred length strings to be confusing. For folks relatively new to Fortran and who don’t understand that the elements of an array have to have a fixed length, the current syntax might imply that an array of variable length strin…

[image] RonShepard: There are a couple of downsides to this approach. The programmer cannot initialize such an array type(string) :: words(1:2)=['first', 'second'] or define such an array as a parameter constant. It would be nice if the language were extended to allow those things, but for now…

[image] wspector: One can write an assignment like: Yes, the assignment works, but not initialization or as a parameter constant. 6 | type(string) :: words(1:2) = [string('first'),string('second')] | 1 Error: Invalid initialization expressi…

The F2023 standard does forbid character array elements having different lengths: 3.3 says an array is a set of scalar data, all of the same type and type parameters, and 7.2 para 2 says a type parameter is either a kind type parameter or a length type parameter. I have reported the bug in the offe…

Thanks for finding that - I had hoped such wording appeared, but I had not found it. As for 10.2.1.3, that’s not a problem I now realize because, as we’ve said before, an array element cannot itself have the allocatable (nor pointer) attribute.

My problem with 10.2.1.3 was due to the declaration character(:),allocatable::a,b,words(:) where the second (:) says words is an allocatable array but the first (:) says the elements have an allocatable length.

Length(s) of allocatable character array?

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DavidB April 6, 2025, 6:16am 2

See the first response in Character array constructor

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Length(s) of allocatable character array?

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