What's wrong with my line continuation syntax?

Question

In a project I've been assigned to I'm asked to compile my code with f77, and I'm trying to get a grip on how to handle the 72 characters per line limit. I'd like to write the following line of code:

!use the numbers to check my indentation...
!2345678901234567890
                  MPI_SEND(slave, 1, MPI_INTEGER, slave, MPI_ANY_TAG, MPI_COMM_WORLD, ierr)

the long indentation before is because the line is inside a couple of blocks, and I'd like to solve this without having to sacrifice code indentation (i.e. readability).

As is, the code is truncated after MP in MPI_COMM_WORLD, so I thought I'd just break the line, and add a line continuation character in column 6. I've seen examples on the net with both + and integer digits as the line continuation characters, so I've tried both the following versions:

!2345678901234567890
                  MPI_SEND(slave, 1, MPI_INTEGER, slave, MPI_ANY_TAG,
     1              MPI_COMM_WORLD, ierr)
                  MPI_SEND(slave, 1, MPI_INTEGER, slave, MPI_ANY_TAG,
     +              MPI_COMM_WORLD, ierr)

Both of them give me a compile error on the first line, saying

                  MPI_SEND(slave, 1, MPI_INTEGER, slave, MPI_ANY_TAG,   
                  1
Error: Unclassifiable statement at (1)

The code resides in a code file named pi.f, I'm compiling with make pi and I have (only) the following in my makefile:

FC = mpif77 
FFLAGS=-Wall

Make shows me that the actual command to compile the file is

mpif77 -Wall pi.f -o pi

What am I doing wrong here? How do I make this work?

if you are doing a lot of this, find an editor that autoindents f77.. emacs for example. — agentp
@george: I've never been an Emacs guy - the (re)learning curve for the keyboard shortcuts that I need to be efficient has just been too steep every time I've tried. Right now I'm using Geany, where I have display options to give me a line at the 7th column (i.e. "start at this line") and everything that sticks out too far on the right on the right turning red. It's good enough for my current needs. — Tomas Aschan

High Performance Mark High Performance Mark · Accepted Answer · 2013-03-26T18:05:41

Before worrying about any line continuation syntax issues you may (or may not) have, I suggest you attend to the error message from the compiler. MPI_SEND is a subroutine, not a function nor a command, it's use should be preceded by the keyword call.

What's wrong with my line continuation syntax?

1 Answers