请问如何用fortran编程计算txt各行累计相加的程序，当遇到-999时跳出这一行，继续向下相加

Question

如题所述

Answer 1

program sumlines
implicit none
real*8 :: r, sums
integer :: i, n = 1000
open (1, file='in.txt')
sums = 0.0
do i = 1, n
read(1,*) r
if (r.ne.-999.) then
sums = sums + r
else
sums = sums +0
endif
enddo
end