invalid character name at (1)

Question

I am trying to compile a fortran code. It will analyze an X file in an Y directory and then create a new file Z with the results. But there is something wrong occurring.

When I write the directory I see that it is too much for one line and then I try to continue it in the next one doing this:

  namech='/home/matheus/Documents/UFABC/IC/Spectra/Elliptical/'
  +          'espec.fits'

But, when I try to compile using the command

gfortran Codigo.f -o TESTE -Lcfitsio -lcfitsio

I get this error message:

 +          'espec.fits'                                           
  1

Error: Invalid character in name at (1)

Can someone help me? Actually I do not know what this error is. The directory is 100% right. And when I move the archives to a simpler directory to be able to write everything in one line, it works! So is there something wrong with the "+"?

Thank you.

Edit1

Actually, when I add "&" in the end of the line, it gives me this error message:

 namech='/home/matheus/Documents/UFABC/IC/Spectra/Elliptical/'&    
 1

Error: Unclassifiable statement at (1) Codigo.f:60.7:

 +          'espec.fits'                                           
  1

Error: Invalid character in name at (1)

And with "//":

 namech='/home/matheus/Documents/UFABC/IC/Spectra/Elliptical/'//   
                                                                   1

Error: Syntax error in expression at (1) Codigo.f:60.7:

 +          'espec.fits'                                           
  1

Error: Invalid character in name at (1)

Edit2

Thank you so much for helping me. Well, I solved the problem switching to the ".f90" form.

Just one more question: do you know why it does not recognize the "c" for comments in the code? Thank you again! :)

Answer 1

This part of your compilation statement:

gfortran Codigo.f 

will treat the source file, with its .f suffix, as fixed form source. This means that a continuation line is indicated by any character (other than a blank or a 0) in column 6.

However, the error message you get suggests that the + in the second line of your snippet is not in column 6 and that the compiler is treating it as the initial character in a new entity name for which it is not valid. The fact that the + is aligned, vertically, with n in the previous line strengthens my suspicion that this may the root of your problem.

Adding the ampersand, as suggested in a now-deleted answer, doesn't actually help in this case if you continue to tell the compiler that it is dealing with a fixed form source file. & is only used for continuation in free form source files. Adding the string-concatenation operator, //, doesn't help either since it is not followed by another string but a line ending. //& would help but is probably unnecessary.

I think you have 2 possible solutions, but choose only one:

1. Stick with fixed form and get the alignment right.
2. Change the file suffix to .f90 which will cause gfortran to treat the source file as free-form.

If you go for option 2 (which I would recommend) you can then either use & at the end of the continued line or you could simply merge the lines. In free-form the maximum line length is 132 characters.

Answer 2

Adding to High Performance Mark's answer:

If you continue with FORTRAN 77, most compilers have an option to increase the allowed line length, e.g., -ffixed-form -ffixed-line-length-none for gfortran. As already stated, Fortran >=90 has line length of 132, so you wouldn't need to split the line.

Finally, if you want to split the line in Fortran >=90, you need two ampersands. In most cases you need one, but to split a string you need two:

namech='/home/matheus/Documents/UFABC/IC/Spectra/Elliptical/&
&espec.fits'