Fortran Retake: Reading an existing file into a fortran code

[angelfaz]

Thank you very much for the reply. I placed the file in the same directory as the program and opened the file before executing and everything was just perfect. But my other problem is that, in my data, there consists of negative numbers. Is there a way to read the positive inputs without the negative ones? I tried adding an IF statement to the code, but still the negative is being read.
I am attaching the a sample of the code i wrote.
Thanks very much

 

[SteamKing]

It's not clear why you don't want to read negative values from your data file.

Can you just test the value read to see if it is less than zero and discard it?

 

[Mark44]

OP, here is your code. I don't see the point in attaching a Word document instead of inserting the code directly into the input pane here.

I tried adding an IF statement to the code, but still the negative is being read.

Where? I don't see that IF statement in your code. It's pretty simple really - each time you read from the file check to see if the number is negative. If so, skip to the next loop iteration.

Program rainfall
!Purpose:
!This program calculates the total monthly rainfall and the average by reading in the values from an opened file.
 IMPLICIT NONE
!List of variables:
CHARACTER(len = 20):: filename  !Input file name
CHARACTER(len = 20)::month      !Month to be read
INTEGER::n = 0  !Number of input values.
INTEGER:: ierror  !Status flag of i/o statement
REAL:: x  !An input data value
REAL:: sum_x = 0  ! Sum of input values
REAL:: x_bar = 0  !Average of input samples

!Prompt the user and get the name of file for input
WRITE(*,*)'enter the name of the file:'
READ(*,*) filename

!Prompt the user for the month
WRITE(*,*)' enter the month:'
READ(*,*) month
!Open the input file 
OPEN (Unit = 3, FILE = filename, STATUS = 'OLD', ACTION = 'READ', IOSTAT = ierror)
 !Check to see if the file opened successfully
errorcheck: IF (ierror > 0) THEN
 WRITE(*,*) filename
ELSE
!file opened successfully. Read input values x from the file
DO
   READ ( 3,*,iostat= ierror)  x
IF ( ierror /= 0) EXIT
 n = n + 1
sum_x = sum_x + x         !Calculate sum

END DO

!Calculate the mean rainfall
x_bar = sum_x / real(n)

!Tell user

WRITE(*,*)'Number of data points = ',n
WRITE(*,*)'Monthly total = ', sum_x
WRITE(*,*)'Monthly average = ', x_bar

!Close input file
CLOSE(Unit = 8)

End if errorcheck

End program rainfall