If you use result instead of res, you don't need to declare or initialize it.
It is the return value available automatically.

Definitely!
A new tag is needed Stupid Practices

This is what people love and hate about C. I find the language almost poetic, sometimes.

I love it when it's done in solutions of fun problems, but I would hate to maintain such code :D

Thanks BDub_88 for taking time to reply. I hope I can contribute too when I become less noob 🙄

Yeah, I just suspect they didn't want to change the wording on the question and techincally you don't need the destination parameter but then the function would have to either alter str in place or allocate memory in the function and free it outside. It's easier to just do it the way they have, though I like the idea of altering the string in place.

Would fail if cm overlows as might happen with arr:
{1,2,...,43}

The description said no need for floats, but double is a kind of float.

@Koistinen. Good catch. See fork.

You could use a directly. No need for p.

The description says it has one parameter but in C it has two parameters as one is convenient preallocated memory for the result.
A little confusing.

Couldn't the array be [7][7] instead?

Those numbers are correct. The test case just has some big numbers in it, that's all. True, they aren't sorted into any kind of order -- but the kata description never promised they would be.

This is for C:
While the probability values look ok, the position values of test #4 in Random_Tests are consistently wrong and seem to be very large and not in order.

11,8
{(-16807268829305383559342375576237254726043224244224.000000, 0.054688), (-16441893419972657829791454368058183971129241108480.000000, 0.109375), (24845527834625349609462642156176811334150853230592.000000, 0.015625), (-8769009823985417509222108996297698117935595257856.000000, 0.234375), (28499281927952606904971854237967518883290684588032.000000, 0.132812), (365375409332725729550921208179070754913983135744.000000, 0.046875), (24480152425292623879911720947997740579236870094848.000000, 0.070312), (28133906518619881175420933029788448128376701452288.000000, 0.085938), (10595886870649046156976715037193051892505510936576.000000, 0.070312), (-2923003274661805836407369665432566039311865085952.000000, 0.039062), (-8038259005319966050120266579939556608107628986368.000000, 0.140625)}

{(-13884265554643577722935005910804688686731359158272.000000, 0.109375), (-7307508186654514591018424163581415098279662714880.000000, 0.156250), (-21191773741298092313953430074386103785011021873152.000000, 0.031250), (-12788139326645400534282242286267476421989409751040.000000, 0.234375), (-30326158974616235552726460278862872657860600266752.000000, 0.078125), (-5115255730658160213712896914506990568795763900416.000000, 0.171875), (-25210903243958075339013563364355882089064836366336.000000, 0.171875), (-2192252455996354377305527249074424529483898814464.000000, 0.046875)}

Might crash if string is empty.