Very Simple Question on Fortran - UNIX Compiling

Apologies if this is too naive or obvious but after a fair bit of searching around, I'm not 100% sure that I understand the fortran/unix interface. My uncertainty is regarding the nature of .src, .f, then .o, and .out files that you run into when compiling fortran programs into a unix executable. It's tough to google file extensions like this. But if you could tell me if I've got this straight, I'd really appreciate it!

.src is the source file which contains the meaty fortran code

.f is the 'host-language specific include file' that tells your fortran compiler a little bit about the source code. It's sometimes interactive.

--- After you've obtained .o or .out files, can throw away the .src and .开发者_JAVA百科f files, yeah?

.o is the binary object file that results from compiling but not linking the fortran .f and .src files. It contains the same meat but now converted into machine-specific instructions? .out is the linked object file(s) which is executable and remains dependent on the .o file(s) and is machine-specific. The .out file extension is not really needed and is often omitted?

I think that covers it. Thanks for any corrects or further descriptions.

Kyle

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Nothing about these file extensions is set in stone; as you said, they can even be omitted, or you can make up your own. However, it makes life far easier if you use the conventional ones.

I've never seen the .src extension. The directory where the source files are located is often referred to as ./src; maybe you've seen this.
Usually, the source code (plain text) is in a file with extension .f or .f90. The first one indicates fixed source form ("old style"), and the second one free source form ("modern"). Some compilers interpret uppercase file extensions (.F and .F90) as an indication that the source has to be run through the preprocessor first. Instead of letting the compiler use the extensions for these interpretations, all this can also be explicitly stated/overruled by passing flags to the compiler.

Compilation of the source code produces object code (the machine-specific instructions you mention), contained in an object file, usually with .o as extension (sometimes .obj, or other). After creating the object files, you could indeed throw away your source code files, but you don't want to do that. You want to fix any bugs you most likely made, and also keep them for future alterations to your program.

The object code has to be linked to produce the final executable. If you have more than one object file, they are tied together, with inclusion of any system/external library code you referred to. On Unix, if you don't specify a name for the executable, the default name it gets is usually a.out. Again, you can overrule this by passing an argument to the compiler.

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No, the Fortran code is usually in .f or .f90 files. In more detail, Fortran source code usually has the extension .f if it uses the fixed source form (the standard source form of Fortran 77 and earlier versions) or .f90 it uses free source form (present from Fortran 90 on).

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After you've obtained .o or .out files, can throw away the .src and .f files, yeah?

No. As an addendum to the answers describing the various suffix conventions, I advise that you don't delete the Fortran source files (the .src or .f files in your description). You'll need these files if you ever want to modify the program, or if you need to investigate and fix errors you notice from running the executable file (a.out).