The maximum length of processor collating sequence

[DataScientist]

The Fortran standard `char (i [,kind] )` returns the character in position i in the processor collating sequence associated with the relevant kind parameter. The value of i must be in the range `0 < i < n - 1`, where n is the number of characters in the processor’s collating sequence. Is there a way to infer the value of `n` in a portable way within the programming environment?

[Steve_Lionel]

Interesting question. I can't think of a reasonable way, offhand. What's your use case? I think some character sets have discontiguous ranges, which could complicate matters.

[DataScientist]

The goal is to replicate `minval`/`maxval` and similar functionalities for scalar character sequences.

These two intrinsics return the maximum/minimum of the corresponding type and kind if the input array has zero size.

For characters, the result of the comparison is determined by the positions in the processor collating sequence.

Therefore, the last character in the collating sequence is required to fully mimic `minval`/`maxval` behavior.

What would `char(i)` behavior be if the collating sequence can be discontiguous?

[Steve_Lionel · Accepted solution]

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@DataScientist wrote:

What would `char(i)` behavior be if the collating sequence can be discontiguous?

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Undefined.

I'll admit that I was not familiar with the behavior of MAXVAL/MINVAL when ARRAY is size zero. It would seem that:

ichar(minval(c))

where c is a zero-sized array of characters, does what you want.

[DataScientist]

excellent clever solution.

[DataScientist]

I also have to admit that I did not know `minval` and `maxval` work with character arrays.