sorting numbers in increasing order...

[kostalibe]

Hi,
I have this code for sorting N numbers X(I) in increasing order.

DIMENSION X(100)
READ (*,*) N, (X(I),I=1,N)
N1=N-1
DO 15 I=1,N1
AMIN=X(I)
M=I+1
DO 25 K=M,N
IF (AMIN.LE.X(K)) GO TO 25
Z=AMIN
AMIN=X(K)
X(K)=Z
25 CONTINUE
15 X(I)=AMIN
WRITE (*,2) (X(I),I=1,N)
2 FORMAT (10(3X,F5.2))
STOP
END

I dont want to read data from keyboard but from a file.And then write the result in to a another file.
Does anyone know how this will work??

Many thanks

 

[xwb]

Change

    READ (*,*) N, (X(I),I=1,N)
...
     WRITE (*,2) (X(I),I=1,N)

to

      OPEN (10, file='input.txt', status='old')
      READ (10, *) N, (X(I), I = 1, N)
      CLOSE (10)
...
      OPEN (20, file='output.txt', status='new')
      WRITE (20, 2) (X(I), I = 1, N)
      CLOSE(20)

10 and 20 are just arbitrary numbers - can be anything you like. Some people like low single digit ones like 1 and 2, some like them in their 10s others in their 100s or 1000s. You can also have them as PARAMETER constants which aren't so error prone.

 

[kostalibe]

thanks a lot, but i need a little more help.
My file,which i want to read and put the data in increasing order, has many many rows(i dont know how many!) and 6 columns.
I only need to read the first column. Then when I execute my program...

program ORDER

DIMENSION X(100)
OPEN (10, file='myfile.DAT', status='old')
OPEN (20, file='output.dat', status='new')
READ (10, *) N, (X(I), I = 1, N)
N1=N-1
DO 15 I=1,N1
AMIN=X(I)
M=I+1
DO 25 K=M,N
IF (AMIN.LE.X(K)) GO TO 25
Z=AMIN
AMIN=X(K)
X(K)=Z
25 CONTINUE
15 X(I)=AMIN
WRITE (20,*) (X(I), I = 1, N)
CLOSE (10)
CLOSE(20)
STOP
END

it shows: user breakpoint code... and says: list-direct I/O syntax error, unit 10, etc....

what is the problem??
thanks a lot again for your kind help

 

[xwb]

1) You are reading N first - is this the number of entries in the file?
2) READ (10, *) will read in free format: not one per line. If you want one per line, do not use an implied do loop: use a normal do loop i.e.

DO I = 1, N
   READ(10,*) X(I)
ENDDO