Extract integers from string in Fortran

Question

I'm using Fortran 90. I have a string declared as CHARACTER(20) :: Folds, which is assigned its value from a command line argument that looks like x:y:z where x, y, and z are all integers. I then need to pick out the numbers out of that string and to assign them to appropriate variables. This is how I tried doing it:

 i=1
 do j=1, LEN_TRIM(folds)
    temp_fold=''
    if (folds(j).neqv.':') then
        temp_fold(j)=folds(j)
    elseif (i.eq.1) then
        read(temp_fold,*) FoldX    
        i=i+1
    elseif (i.eq.2) then
        read(temp_fold,*) FoldY 
        i=i+1
    else
        read(temp_fold,*) FoldZ 
    endif
 enddo

When I compile this I get errors:

unfolder.f90(222): error #6410: This name has not been declared as an array or a function. [FOLDS]

[stud2@feynman vec2ascii]$ if (folds(j).neqv.':') then syntax error near unexpected token `j' [stud2@feynman vec2ascii]$ --------^

unfolder.f90(223): error #6410: This name has not been declared as an array or a function. [TEMP_FOLD]

[stud2@feynman vec2ascii]$ temp_fold(j)=folds(j)

syntax error near unexpected token `j'

How can I extract those numbers?

May I suggest that you make the compiler output clearer, to benefit posterity? I would have had a go at it, but it's better to get it exactly right. — francescalus
– francescalus, Commented Jan 26, 2014 at 23:26

M. S. B. · Accepted Answer · 2014-01-26 22:41:48Z

2

You can use the index intrinsic function to locate the position in the string of the first colon, say i. Then use an internal read to read the integer xfrom the preceding sub-string: read (string (1:i-1), *) x. Then apply this procedure to the sub-string starting at i+1 to obtain y. Repeat for z.

P.S. Are your error messages from bash rather than a Fortran compiler?

answered Jan 26, 2014 at 22:41

M. S. B.

29.5k2 gold badges52 silver badges75 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Anton B Over a year ago

They are from fortran compiler, when i copied to clip board it inserted bash in there.

francescalus · Accepted Answer · 2014-01-26 23:56:18Z

1

With folds a character variable, to access a substring one needs a (.:.). That is, to access the single character with index j: folds(j:j).

Without this, the compiler thinks that folds must be either an array (which it isn't) or a function (which isn't what you want). This is what is meant by:

This name has not been declared as an array or a function.

But in terms of then solving your problem, I second the answer given by @M.S.B. as it is more elegant. Further, with the loop as it is (with the (j:j) correction in both folds and temp_fold) you're relying on each x, y, and z being single digit integers. This other answer is much more general.

edited Jan 26, 2014 at 23:56

answered Jan 26, 2014 at 23:04

francescalus

33k28 gold badges86 silver badges128 bronze badges

1 Comment

Anton B Over a year ago

Thanks, if i use (j:j) then my method works. I like MSB's method, save from those ifs and a loop.

Collectives™ on Stack Overflow

Extract integers from string in Fortran

2 Answers 2

1 Comment

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related