I went into this thinking: C is basically cleaned up FORTRAN, right? I know C? This should be easy, right? Right off the bat I find there will be a lot of difficulties entirely not of the kind I'm used to in programming. After a brief adventure with accidentally naming my file .f and not .f90 causing horrific and baffling errors, I run a hello world off the Internet. There's a space before the printout. Hm, how do I turn that off?

https://stackoverflow.com/a/31236043

Oh my fuck, *what*?

I get frustrated with C all the time for being fundamentally a 70s language. It may be I'm about to learn the pain of using a *50s language*.

(Alternately, I hear modern FORTRAN has all kinds of fancy niceties like operator overloading and might not resemble traditional FORTRAN all that much. But then I have the problem if I pick up a random tutorial it's hard to guess which *decade's* standard it's teaching me from, or if it's the GNU extension, if the GNU extension is that different, etc.)

Just learned FORTRAN has an aint() function

Don't that just beat all

Here is my current program. At the moment, all it does is take a command line argument (a path) and attempt to open the specified file. I build it with `gfortran src/puzzle.f90 -std=f2023 -o program`

https://github.com/mcclure/aoc2024/blob/822e460f81b944c21ca675303b868c45b22a4c2b/04-01-wordsearch/src/puzzle.f90

I'm having two problems, one serious, one unserious.

The unserious problem: I want to abort if the # of arguments is bad. If I do "error stop", it prints a backtrace, which I didn't ask for. If I do "call abort", gfortran fails to link ("undefined reference to 'abort_').

Here's my serious FORTRAN problem (code link in previous post):

The recommended GET_COMMAND_ARGUMENT function seems to assume you know the length of the argument ahead of time. Obviously, I don't.

https://gcc.gnu.org/onlinedocs/gfortran/GET_005fCOMMAND_005fARGUMENT.html

It allows me to pass in an `allocatable` string, but I believe it is leaving that string of length 0 if I do not ALLOCATE() it, and the fetched string is ''. Is there a way to get the length of a command-line argument before GET-ing it?

I see GET_COMMAND, but that's… awkward

…hm. I am concerned.

According to the FORTRAN working group

https://wg5-fortran.org/N2201-N2250/N2212.pdf

As of the 2023 standard, an un-allocated deferred-length variable may have its length set by calling intrinsic procedures; they give GET_COMMAND as an example specifically, and StackOverflow users assert GET_COMMAND_ARGUMENT is also included.

I don't get this behavior. My argument is being input as ''.

Do you think this means my code (linked above) is wrong, or that gfortran -std=f2023 is nonconformant?

Oh my hell lol, I sincerely believe I have found a bug (standard nonconformance) in GNU FORTRAN 14.2.0 and I have a repro case

https://github.com/mcclure/aoc2024/blob/b31be91adb5a0721f97e2ba8f145da4f36129753/04-01-wordsearch/src/puzzle.f90

Am I going to have to figure out how to report a bug on GNU. Geez. Is this going to be like the bureaucracy planet scene in Jupiter Rising

Now that I have successfully figured out how to read an argument from the command line without knowing its length ahead of time, I am stuck on figuring out how to read a line of text from a file without knowing its length ahead of time. Apparently not an expected FORTRAN use case. I think the trick I was using before will not work, or at least, I *think*

read(10,"(a)",size=line_length,advance='NO') line_in

should read a line without advancing the filehandle and save the size. But it saves 0.

Incidentally, I am very comfortable usually with reading language specifications, but I got hold of a copy of the FORTRAN 2008 spec and… this is one of the least friendly language specifications I've ever seen, when reading it to try to determine how a program should be written.

(Trivia: When the image on the right says something like "the value must be YES or NO" what they mean is "the value must be 'YES' or 'NO'.)

FORTRAN 2008 spec 9.1:
"A file is composed of either a sequence of file storage units (9.3.5) or a sequence of records… A file composed of file storage
13 units is called a stream file."

The definition of "file storage units" (9.3.5):
"A file storage unit is the basic unit of storage in a stream file or an unformatted record file."

The linked definition of "Stream file" (1.3.139)
A file composed of a sequence of le storage units (9.1)

YOU ASSHOLES, THIS DEFINITION IS CIRCULAR!

git discovery: you cannot check a file you do not have permissions to into a repository.

problem: my repo contains a directory of test files. this directory contains a second directory of "invalid" tests, i.e., tests that the program is *expected* to fail on (and if it doesn't fail cleanly that's an error). one of the "invalid" tests is a file the program doesn't have read permissions to.

I cannot check my "file with no read permissions" test case into the repository :(