I am trying to put an input string into sub-string arrays. The number of data in the input file are less than 10 but unknown. The number of spaces between each data is also unclear.
Example:
Asd B Cwqe21 Ddsw Eww
I am quite novice to Fortran, so I do not know which format I should use. My problem is that I do not know the number of data (here I assumed that there are 5), so how can I make the code work?
I tried the following which did not work:
CHARACTER (LEN=100), DIMENSION(10) :: string
READ (1,*) (string,I=1,10)
It seems that the error I got was because there was no 6th string to read and put into string(6).
I tried using the "Index" to find the space, but since I do not know how many spaces are in the string, it did not help me.
I don't know if this is more or less elegant/efficient than the standard approach in M.S.B's comment, but an interesting alternative.
integer istart,nw
character (len=100) line,wd,words(100)
open(1,file='t.dat')
read(1,'(a)')line
istart=1
nw=0
do while(len(trim(line(istart:))).gt.0)
read(line(istart:),*)wd
istart=istart+index(line(istart:),trim(wd))+len(trim(wd))
nw=nw+1
words(nw)=trim(wd)
enddo
write(*,*)trim(line)
write(*,*)('/',trim(words(k)),k=1,nw),'/'
end
An inefficient approach that is simple to program is to try to read the maximum number of items, and if this fails to successively try to read one fewer items until the read is successful, as shown below:
program xread_strings
integer, parameter :: nw = 10
character (len=1000) :: text
character (len=20) :: words(nw)
integer :: i,ierr,nread
text = "Asd B Cwqe21 Ddsw Eww"
nread = 0
do i=nw,1,-1
read (text,*,iostat=ierr) words(:i)
if (ierr == 0) then
nread = i
exit
end if
end do
if (nread > 0) write (*,*) "read ",nread," words: ",("'"//trim(words(i)) // "' ",i=1,nread)
end program xread_strings
! g95 Output:
! read 5 words: 'Asd' 'B' 'Cwqe21' 'Ddsw' 'Eww'
Related
I'm writing in fortran (90). My program must read file1, do something with every line of it and write result to file2. But the problem - file1 has some unneeded information in first line.
How can I skip a line from input file using Fortran?
The code:
open (18, file='m3dv.dat')
open (19, file='m3dv2.dat')
do
read(18,*) x
tmp = sqrt(x**2 + 1)
write(19, *) tmp
end do
First line is a combination of text and numbers.
One possible solution has already been presented to you which uses a "dummy variable", but I just wanted to add that you don't even need a dummy variable, just a blank read statement before entering the loop is enough:
open(18, file='m3dv.dat')
read(18,*)
do
...
The other answers are correct but this can improve conciseness and (thus) readability of your code.
Perform a read operation before the do loop that reads whatever is on the first line into a "dummy" variable.
program linereadtest
implicit none
character (LEN=75) ::firstline
integer :: temp,n
!
!
!
open(18,file='linereadtest.txt')
read(18,*) firstline
do n=1,4
read(18,'(i3)') temp
write(*,*) temp
end do
stop
end program linereadtest
Datafile:
This is a test of 1000 things that 10
of which do not exist
50
100
34
566
!ignore the space in between the line and the numbers, I can't get it to format
open (18, file='m3dv.dat')
open (19, file='m3dv2.dat')
read(18,*) x // <---
do
read(18,*) x
tmp = sqrt(x**2 + 1)
write(19, *) tmp
end do
The line added just reads the first line and then overwrites it with the seconde on the first iteration.
I am working on ciphering program, where ull put text and it will convert it into coded message. I stick and point where I dont know how to split len into sepparate characters. Is it even possible?
Yes, you can split a string into a character array. If chararray = "abcdefg" then you can have an array like ca(1) = chararray(1:1), ca(2) = chararray(2:2) ...
ca(7:7) = chararray(7)
This can also be done in a do-loop using the iachar and achar functions.
program test
character*7 :: stringin
integer :: single_character
stringin = 'message'
do i = 1, len(stringin), 1
single_character = iachar(stringin(i:i))
write(*,*) achar(single_character)
end do
end program
This creates an integer representation of the letters with iachar and converts them back with achar. This may be helpful if using a mathematical expression to do the encoding.
More information can be found here
I am trying to repeat the string "k" to match the length of "text" without going over the length. So it would output "treetreetreetreetreet" and not "treetreetreetreetreetree". I really dont know where to start other than just outputing more characters than needed.
PROGRAM test
IMPLICIT NONE
CHARACTER*30 :: text, k
INTEGER :: times
text = 'hello my name is anon'
k = 'tree'
times = (LEN_TRIM(text)/LEN_TRIM(k)) + 1
WRITE(*,*) REPEAT(k,times)
END PROGRAM test
First, your sample program as-is doesn't produce treetreetreetreetreetree as you expect, it actually produces tree tree tree .... When you pass the string k to REPEAT, the spaces after tree also get repeated. You should trim the string before repeating it, such as REPEAT(trim(k),times).
There are several ways to solve your main problem - I recommend using what you have so far but reducing the final result to the length you want - in this case LEN_TRIM(text). A good way to do this is to store the output of REPEAT in a temporary variable and output only a subset of this final string.
With both of these modifications and some other cleanup, your code looks like:
program main
implicit none
character(len=30) :: text, k, str
integer :: times
text = 'hello my name is anon'
k = 'tree'
times = (LEN_TRIM(text)/LEN_TRIM(k)) + 1 ! -- Note integer division
str = REPEAT(trim(k),times)
write(*,*) str(1:LEN_TRIM(text))
end program main
which gives the desired output
> gfortran main.f90 && ./a.out
treetreetreetreetreet
I have the following code:
program main
character (len=15) :: abc = "te st tex t"
print *, trim(abc)
end program main
Which outputs:
te st tex t
I excepted all the whitespace to be removed but it wasn't. How can I remove all the whitespace from the string?
Trim will remove spaces only at the edges, not in the middle (this is common behaviour on almost all languages/libraries). If you want to remove all spaces in the string, you will have to create your own function to do this, iterating through the string.
Ex.:
program Test
implicit none
! Variables
character(len=200) :: string
! Body of Test
string = 'Hello World 7 9'
print *, string
call StripSpaces (string)
print *, string
contains
subroutine StripSpaces(string)
character(len=*) :: string
integer :: stringLen
integer :: last, actual
stringLen = len (string)
last = 1
actual = 1
do while (actual < stringLen)
if (string(last:last) == ' ') then
actual = actual + 1
string(last:last) = string(actual:actual)
string(actual:actual) = ' '
else
last = last + 1
if (actual < last) &
actual = last
endif
end do
end subroutine
end program Test
This was tested on intel compiler, not on gfortran, but I think it will work.
I was able to do this using the variable string library described here ( http://schonfelder.co.uk/is1539-2-99.htm ). The source code link is found in the introduction section of the ISO document.
Here is the code
program Console1
use ISO_VARYING_STRING
implicit none
! Body of Console1
character(LEN=50) :: text = 'Hello World John Mary '
character(LEN=50) :: res
print *, trim(text)
! 'Hello World John Mary'
res = REPLACE(text,' ','', every=.TRUE.)
print *, trim(res)
! 'HelloWorldJohnMary'
end program Console1
Here's a dirty, shameful way to eliminate the spaces. This is only likely to work if a compiler lays out a length-15 string in the same order and space as it would a 15-element array of characters. While this is likely to be true, and in my recent experience is true, it is not guaranteed to be so by the standard. That aside, this approach may be good enough.
! declarations
CHARACTER (len=15) :: abc = "te st tex t"
CHARACTER, DIMENSION(LEN(abc)) :: abc_array
! or CHARACTER, DIMENSION(:), ALLOCATABLE :: abc_array if your compiler supports
! automatic allocation
! transfer the string into an array of characters
abc_array = TRANSFER(abc,abc_array)
! eliminate the spaces, and transfer back to the string
abc = TRANSFER(PACK(abc_array,abc_array/=' '),abc)
! now all the spaces are at the end of abc so the following statement writes the
! string with no spaces
WRITE(*,*) TRIM(abc)
Use this approach at your own risk.
For those averse to TRANSFER perhaps a nice little recursive function would appeal. As written this depends on Fortran 2003's ability to automatically allocate character scalars, but it shouldn't be too hard to modify if your compiler doesn't support this feature yet.
RECURSIVE FUNCTION stripper(string,ch) RESULT(stripped)
CHARACTER(len=*), INTENT(in) :: string
CHARACTER, INTENT(in) :: ch
CHARACTER(:), ALLOCATABLE :: stripped
IF (LEN(string)==1) THEN
IF (string==ch) THEN
stripped = ''
ELSE
stripped = string
END IF
ELSE
IF (string(1:1)==ch) THEN
stripped = stripper(string(2:),ch)
ELSE
stripped = string(1:1)//stripper(string(2:),ch)
END IF
END IF
END FUNCTION stripper
You can try this:
program test
!erase blank space in a string
!run over every character of the string and just take every non-blank in other variable.
implicit none
character (len=100) str1,str2
integer i
str2='' !in this variable will be save non-blank spaces
str1=' a b c de ' !Test string with blank spaces
write(*,*)len_trim(str1), str1
do i=1,len(str1)
if (str1(i:i).ne.' ')str2=trim(str2)//trim(str1(i:i))
end do
write(*,*)len_trim(str2), str2
end
I'm trying to write a simple Fortran code, for practicing. It is supposed to multiply numbers in a range. Each time, the resulting product is converted into a string because I want to see if it consists of the same digits.
I tested the way I transform an integer into a string and typed the components of the string, and everything was going correctly. Then, I need to compare the components of the string, for which I use string(number:number). But I couldn't get the code to do this correctly.
Here's the code and the output:
program test
implicit none
character(10) myString
character(1) a,b,c,d,e,f
integer::i,j,k
do i=900,901,1
j=900
k=i*j
write(*,*)'k =', k
write(myString,'(i10)') k
write(*,*)'myString = ', myString
a=myString(1:1)
b=myString(2:2)
c=myString(3:3)
d=myString(4:4)
e=myString(5:5)
f=myString(6:6)
print*,a,b,c,d,e,f
if (d==f) then
print*,'hobla'
else
print*,'fobla'
end if
end do
stop
end program test
So I defined characters: a,b,c,d,e,f to contain the components of the string. And used myString(i:i) to locate each component and store it in one of the characters a,b,c,d,e,f.
But it seems only the first two are working correctly, the rest is not being stored!
Output:
k = 810000
myString = 810000
81
fobla
k = 810900
myString = 810900
81
fobla
Notice 81. This was supposed to give 810000 the first time, and print "hobla". And give 810900 the second time and print "fobla". But this didn't happen!
Can anybody show me how to let myString accept the zeros as characters?
This statement
write(myString,'(i10)') k
writes the value of k into a 10-character field. Since k has only 6 significant digits the first 4 characters in myString are filled with blanks. Then you assign the first 6 characters of myString (that is 4 blanks and the digits 8 and 1) to the variables a,b,c,d,e,f and print them out -- 4 blanks and 2 digits.
Try printing out the other characters in positions 7..10 of myString and you should see your 'missing' digits.
Okay, so I figured out the problem. Consider the following modifications to your code:
program test
implicit none
character(10) myString
character(1) a,b,c,d,e,f
integer::i,j,k
do i=900,901,1
j=900
k=i*j
write(*,*)'k =', k
write(myString,'(i10)') k
write(*,*)'myString = ', myString
a=myString(1:1)
b=myString(2:2)
c=myString(3:3)
d=myString(4:4)
e=myString(5:5)
f=myString(6:6)
write(*,*) a
write(*,*) b
write(*,*) c
write(*,*) d
write(*,*) e
write(*,*) f
if (d==f) then
print*,'hobla'
else
print*,'fobla'
end if
end do
stop
end program test
The resulting output is:
k = 810000
myString = 810000
8
1
fobla
k = 810900
myString = 810900
8
1
fobla
This happens because the I format right-justifies numbers when printed. So there is a bunch of leading white-spaces because your number is only 6 digits while your string you are writing into is 10. So you get 4 leading spaces.
If you change your format string so you have:
write(myString,'(i10.10)') k
then instead of padding with spaces it will pad with 0's. That way you can always have digits to compare if you would rather.