Error when reading in float in Fortran

Question

This should be quite simple, but I can't manage to read in a floating point number in Fortran. My program test.f looks like this:

  PROGRAM TEST
  open(UNIT=1,FILE='test.inp')
  read(1,'(f3.0)')line

  STOP
  END

The input file test.inp simply contains a single float: 1.2

Now the compiling of my testfile goes fine, but when I run it I get an error:

At line 4 of file test.f (unit = 1, file = 'test.inp')

Fortran runtime error: Expected REAL for item 1 in formatted transfer, got INTEGER

(f3.0)

^

I've tried different modifications of the code and also googling for the error message, but with no result. Any help would be greatly appreciated!

Regards, Frank

Answer 1

Your variable line is implicitly defined as integer. This doesn't work with thef edit descriptor. If you want to read an integer use i edit descriptor (i3 for example). Otherwise declare line as real to math the "f" descriptor.

Note beside: the .0 is not a problem, because if Fortran gets a number with decimal point the .0 part in the descriptor is ignored. It is only used when an number without a decimal is entered and then it uses the number behind the decimal point in the desciptor to add a decimal point into the right place. For with F8.5, 123456789 is read as 123.45678. More ont this here http://software.intel.com/sites/products/documentation/hpc/compilerpro/en-us/fortran/lin/compiler_f/lref_for/source_files/pghredf.htm .