Fortran runtime error: Bad integer for item 1 in list input? Not sure why

Question

Below is the current program, everything checks out to me, except when I execute the program itself it gives me this error.

Fortran runtime error: Bad integer for item 1 in list input.

The first number is 60000.

    implicit none
    
    !declaring the single precision for real numbers, array, and variables.
    integer :: i, firstnumber
    real*4 :: average, sum_, standarddeviation
    
    real*4, allocatable :: arrayone(:)!making sure that the array is single precision real
    
    open(unit=1,file="C:\cygwin64\data sets for labs and assignments\Numbers.txt")!opening file
    
    do 
        read(1,*)firstnumber!reading the first number
    end do

    allocate(arrayone(firstnumber))!allocating the array with the first number variable obtained from previous statement
    
    close(1)
    
    do i = 2, firstnumber
    
    open(i,file="C:\cygwin64\data sets for labs and assignments\Numbers.txt")
        read(i,*)
        
        sum_ = Sum(arrayone) !sums all of the numbers from arrayone
        
        average = Sum_/firstnumber 
        
        standarddeviation = sqrt(sum_ - average) * (sum_ - average)!calculates the standard deviation of the data set
        
        close(i)
    end do
    print*,"Average = "
    print*,"Standard Deviation = "
    
    deallocate(arrayone)!Deallocating arrayone
    
    
    print*,"Done!"
    
    end program Assignmentthree

Answer 1

To expand on francescalus' and Vladimir F's comments:

Catching bugs

The simplest way of debugging a program is adding a bunch of print statements. If you add these to your code, like

    implicit none
    
    !declaring the single precision for real numbers, array, and variables.
    integer :: i, firstnumber
    real*4 :: average, sum_, standarddeviation
    
    real*4, allocatable :: arrayone(:)!making sure that the array is single precision real
    
    open(unit=1,file="C:\cygwin64\data sets for labs and assignments\Numbers.txt")!opening file
    
    do 
        read(1,*)firstnumber!reading the first number
        print *, 'firstnumber = ', firstnumber
    end do

    allocate(arrayone(firstnumber))!allocating the array with the first number variable obtained from previous statement
    
    close(1)
    
    do i = 2, firstnumber
    
    open(i,file="C:\cygwin64\data sets for labs and assignments\Numbers.txt")
        read(i,*)
        
        print *, 'arrayone = ', arrayone
        
        sum_ = Sum(arrayone) !sums all of the numbers from arrayone
        
        print *, 'sum_= ', sum_
        
        average = Sum_/firstnumber 
        
        print *, 'average= ', average
        
        standarddeviation = sqrt(sum_ - average) * (sum_ - average)!calculates the standard deviation of the data set
        
        print *, 'standarddeviation= ', standarddeviation
        
        close(i)
    end do
    print*,"Average = "
    print*,"Standard Deviation = "

then you can see what your program is actually doing, and work out what's going wrong.

Your current error

Your first problem is that the lines

do 
  read(1,*)firstnumber!reading the first number
end do

are performing the read operation multiple times. It will literally try to read integers from the file forever. Obviously the file is finite, so eventually it runs out of valid things to read, and throws the error you are seeing.

To fix this, you should simply get rid of the infinite loop, by removing the lines do and end do.

The empty read

Your next problem is the statement

read(i,*)

This reads from the file you just opened, but doesn't store the results anywhere. It looks like you're trying to populate the arrayone array, which you would do like

read(i,*) arrayone(j)

where j is the index of arrayone corresponding to the element which you want to fill.

In a loop

The other problem you have is that you're doing a lot of things inside a loop which you should be doing outside the loop. As it stands, the code

do i = 2, firstnumber
  open(i,file="C:\cygwin64\data sets for labs and assignments\Numbers.txt")
  read(i,*)
  sum_ = Sum(arrayone)
  average = Sum_/firstnumber 
  standarddeviation = sqrt(sum_ - average) * (sum_ - average)
  close(i)
end do

will:

• open the file
• read the first number in the file, but not store it anywhere
• calculate the sum, average and standard deviation of the entire array arrayone, even though most of the elements of arrayone are not yet filled.
• close the file

and it will do all of this over and over again, firstnumber times.

I suspect that what you want to do is read the firstnumber elements of arrayone from lines 2 through firstnumber+1 of the file, and only then (after the loop) calculate the sum, average, and standard deviation of arrayone.

In order to read multiple rows from your file, you should only open it once (at the statement open(unit=1...), and only close it once (using close(1), but at the end of your program). Each read statement should then read from the same file (so each should be read(1,...).