Read lines in Fortran 77 and cast strings to numbers

Question

I have a text file which looks like this:

7000
1.54
-0.32

What I'd like to do is to read from file, line by line, and assign each of the numbers to a numerical variable. There are always 3 lines with numbers, but I don't know the length of numbers. They may be integer, float, negative. How can I achieve this?

And for the Fortran 77. Yeah, I know. But it's not my call to use it.

Answer 1

This is for reading in your file:

integer :: i
real    :: a, b

open( file='filename.txt', unit=1234, status='old' )
read(1234,*) i
read(1234,*) a
read(1234,*) b
close(1234)

And this is for casting a string to real using internal I/O:

character(len=10) :: str = '1.23e1'
real    :: a

read(str,*) a