Learn modern fortran.
If you browse my repositories on here, you will see I've been up and down the block when it comes to programming languages. I started using modern Fortran just to see what it's like.
The approach was: "This language is so old this probably won't even compile on a modern machine. If it does it's probably terrible to use."
Needless to say, that was a very wrong assumption.
Modern Fortran is a very down to business language. It's a delight to use. You get a low level language with high level concepts. When you need to talk to C for things Fortran has no concept of (like file systems), it's easy. It also seems to be an extremely fast language to top it off.
Tutorial 1 and 2 are in the root of this. But to see the rest, follow these links for the Markdown files and accompanying source code.
todo: put all the links here
Implicit save: (Thanks to Verlio_H for notifying that this is a common pitfall) If you initialize a variable in a type, it just becomes the default. If you initialize a variable in a subroutine or a function, it implicitly gets the save attribute. This will maintain state across each call of the function. With the default initializer being it's initial value.
ways to define 32 bit floats: real(4) real(real32) real(c_float)
ways to define 64 bit floats real(8) real(real64) real(c_double)
(Just use C types so it's easier to understand)
Allocatable - Will automatically deallocate once the variable goes out of scope. Do not manually deallocate cause that's dumb. Pointer - Will NOT automatically deallocate.
NEVER, set this to value in a type method or IT WILL blow up!
in C:
(For C bindings)
const char * would be interopped as character(kind = c_char), intent(in)
This is because C does pointer arithmetic on the location we give it and we can use it to our advantage. Fortran will pass by reference by default. You could consider this &my_variable in C.
You must ensure that the string is null terminated. You can do this with string//achar(0)
const char ** would be interopped as character(len = *, kind = c_char), intent(in) (if you only want 1)
This one, I am still unsure why we need the length component. But I'm sure someone will tell me eventually.
Back to fortran:
character(len = :), allocatable is a dynamic length string in the heap.
BUT
That's not the same as character, dimension(:), allocatable because the former is scalar (1 value, [aka not an array]) and this one is an array of characters.