Error: Nonnegative width required in format string at (1)

Question

I'm trying to compile a piece of code with gfortran and it's failing with the following error: ``` Error: Nonnegative width required in format string at (1) ../src/powmes.f90:410.20: write(lunit,'(I,E,E,E)') wavenum(k),power(k),nmodes(k),errorexpan(k) 414 if (filepower_fold(1:1) /= '#') then 415 fileout=trim(filepower_fold)//'.waven' 416 if (verbose) write(*,*) 'Output '//trim(fileout) 417 open(file=fileout,form='formatted',status='unknown',unit=lunit,err=2) 418 do k=0,ngrid/2 419 do ifold=0,nfoldpow-1 420 write(lunit,'(I,$)') waven(k,ifold) 421 enddo 422 write(lunit,'(I)') waven(k,nfoldpow) 423 enddo 424 close(lunit) ``` How can I compile this?

Accepted Answer

Try changing the format string `I` to `Iw` where `w` is a positive number. Same with `E`, only use `Ew.d`. For explanation see, for example, this link: http://www.cs.mtu.edu/~shene/COURSES/cs201/NOTES/chap05/format.html

Beware though: using, say, `I3` for writing out 1234 might print `***`, so make sure your formats are wide enough.

EDIT: See @M.S.B.'s answer on how to avoid problems with integer formats.

Error: Nonnegative width required in format string at (1)

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