问题
Description of the file: The STL file consists of
solid <solid_name>
facet normal n1 n2 n3 (the triangles normal vector)
outerloop (one of the markers I want to read)
v1 x1 y1 z1
v2 x2 y2 z2 (three vertex of the triangle/facet)
v3 x3 y3 z3
endloop
end facet
endsolid
The idea is to read the information in each line. First, I'm trying !to read the first line:solid
program Leitura
!use, intrinsic :: trim
implicit none
integer ilo, ierror, ihi, ios, iunit, num_text, len_blanck,
len_word,
len_text, i
character(len=80) :: filename
character(len=:), dimension(:), allocatable :: text, lenc
character(len=:), dimension(:), allocatable :: word
character(len=:), dimension(:), allocatable :: blanck
len_blanck=1
len_word=11
len_text=256
allocate(character(len=len_blanck) :: blanck(1))
allocate(character(len=len_word) :: word(1))
allocate(character(len=len_text) :: text(1))
allocate(character(len=len_text) :: lenc(1))
blanck= " "
ierror = 0
iunit=10
filename="Esfera.stl"
!Opening the STL file
open(unit=iunit, file=filename, status='old', access='stream', form='unformatted')
! If NUM_TEXT is zero, then initialize TEXT.
!
if ( num_text <= 0 ) then
num_text = 0
text = blanck
end if
!
! If TEXT is blank, try to read a new line from the file.
if ( ios /= 0 ) then
ierror = 1
word = blanck
text = blanck
return
end if
num_text = num_text + 1
!Reading the first line of information- should be solid name, aka, ! !the name of the solid
read ( iunit, '(a)', iostat = ios ) text
do i=1,len(text)
if ( text(i)==blanck ) then
word = blanck
return
end if
end do
!
! Extract the next word from TEXT into WORD and return.
!
lenc = len_trim ( text )
!
! Find ILO, the index of the first nonblank in TEXT.
!
ilo = 1
do while ( text(ilo:ilo) == blanck )
ilo = ilo + 1
end do
!
! Find IHI, the index of the last consecutive nonblank after the one
! at ILO.
!
ihi = ilo
do while ( ihi+1 <= lenc )
if ( text(ihi+1:ihi+1) == blanck ) then
exit
end if
ihi = ihi + 1
end do
!
! Set WORD.
!
word = text(ilo:ihi)
!
! Slide TEXT to the left.
!
if ( ihi+1 <= lenc ) then
text = text(ihi+1:)
else
text = ' '
end if
return
end program Leitura
回答1:
I don't have the time to write a complete answer but the following fragments should get you started towards a working code.
First off, I think you're going in the wrong direction by trying to parse the STL file as you read it. The STL file format is fairly clean with little, in practice, variation between one example and the next. It's not like some file formats with a thousand different types of line and little clue what's coming next. We'll start by assuming that the input file is well structured. And we'll start with a code that has almost no error processing at all because:
- almost none should be needed;
- including it would serve to bury the important parts of this answer into lots of ifs and elses; and
- unless you are planning to write code to repair broken STL files, the only error processing necessary is to report failure to read the solid from the file.
We will start, of course, with some data structures, specifically one for the solid and one for the facets. Like this:
TYPE facet
REAL, DIMENSION(3) :: normal
REAL, DIMENSION(3,3) :: vertices
END TYPE facet
TYPE solid
CHARACTER(len=64) :: label
TYPE(facet), DIMENSION(:), ALLOCATABLE :: facets
END TYPE solid
TYPE(solid) :: model
I'll wrap the code to read the file into a function, and use it like this:
model = read_solid('filename.stl')
Now, to the meat of it, the function definition
FUNCTION read_solid(fn) RESULT(mdl)
! Read solid from file fn
CHARACTER(*), INTENT(in) :: fn
TYPE(solid) :: mdl
! Local variables
INTEGER :: nu
INTEGER :: ix, jx, num_facets
CHARACTER(len=132) :: line
CHARACTER(len=8) :: word1, word2
! Executables
num_facets = 0
OPEN(newunit=nu, file=fn, status='old')
Read the file, count the number of facets, allocate space for them, then rewind
ios = 0
! Now find out how many facets there are in the file
DO WHILE (ios==0)
READ(nu,'(a132)',iostat=ios) line
! Count the facets in the file
line = ADJUSTL(line)
IF (line(1:5)=='facet') num_facets = num_facets+1
END DO
ALLOCATE(mdl%facets(num_facets))
REWIND(nu)
Read the file again from the beginning, get the solid on this pass:
ios = 0
! Ignore any leading blank lines
sol: DO WHILE (ios==0)
READ(nu,'(a132)',iostat=ios) line
! If the line is empty, get the next one
IF (LEN_TRIM(line)==0) CYCLE sol
Trim any leading spaces from the line using adjustl
line = ADJUSTL(line)
IF (line(1:5)=='solid') THEN
! We've already read the line from the file, now use an
internal read
READ(line,*) word1, mdl%label
EXIT sol
ELSE ! The line didn't start with 'solid'
! Do something
END IF
END DO sol
The variables word1 and word2 are used to 'catch' strings we're not
really interested in, their contents are ignored. The next block reads the facets.
fct: DO ix = 1, num_facets
DO WHILE (ios==0)
READ(nu,'(a132)',iostat=ios) line
IF (LEN_TRIM(line)==0) CYCLE fct ! ignore any blank lines
line = ADJUSTL(line)
IF (line(1:5)=='facet') THEN
READ(line,*) word1, word2, mdl%facets(ix)%normal
READ(nu,*) aline ! this should be 'outer loop' and we ignore it
DO jx = 1, 3
READ(nu,*) word1, mdl%facets(ix)%vertices(jx,:)
END DO
ELSE ! The line didn't start with 'facet'
! Do something
END IF
END DO
END DO fct
CLOSE(nu)
! If anything has gone wrong reading the file, return an empty solid.
IF (ios/=0) DEALLOCATE(mdl%facets)
END FUNCTION read_solid
The main difference between my approach and OP's is that I rely on list-directed input to take care of finding fields in lines, and in reading strings, reals, etc, properly. If the STL file is clean this is a sensible approach, if you're working with dirty STL files, fix them at source.
And, finally, this doesn't actually answer OP's question(s) about how to read strings character-by-character and interpret them. Nor does it fix any of the errors manifest in the code OP posted.
来源：https://stackoverflow.com/questions/57738862/how-to-iterate-over-character-strings-with-numbers-words-and-blancks-in-fortran