Re: Creating C array

[trtt]

I'm not sure if I'm fit to improve the docs because I'm not good enough with 
nim's internal things and not good with english either. Maybe I'll try when I 
become better with either of them ;)

Re: Creating C array

[cblake]

You're welcome. Nim core devs are **_very_** willing to work with any and all 
comers on pull requests to improve documentation. Ignorance by otherwise 
reasonably patient and resourceful newcomers is **_not_** easy to simulate (in 
any project, really). In some ways it's a resource that decays with value as 
people learn their way around.

I agree that foreign function interface helper procs like those mentioned 
probably deserve a section somewhere, probably linked to from the area you 
mention. I mean, there is the `system.nim` module documentation, but it's kind 
of its own problem area.

Re: Creating C array

[trtt]

Thank you!

I wish the docs had mentioned this -

[https://nim-lang.org/docs/backends.html](https://nim-lang.org/docs/backends.html)

Re: Creating C array

[cblake]

Nim defines a 


proc allocCStringArray*(a: openArray[string]): cstringArray


Run

in the `system` module (no need to explicitly `import` it). There is also a 
corresponding: 


proc deallocCStringArray*(a: cstringArray)


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You probably want to use those two calls.

Re: Creating C array

[trtt]

Corrected:



proc kget*(elems: seq[string]): string =
  var arr: CArray[cstring]
  arr[0] = "start"
  var i = 1
  for elem in elems:
arr[i] = elem
i += 1
  var size: cint = cast[cint](elems.len() + 1)
  return $fn(size, addr arr)# tried it with unsafeAddr too


Run

Re: Creating C array

[trtt]

When I load the array manually, it works(somewhat):


var arr: CArray[cstring]
arr[0] = "start"
arr[1] = "arg1"
arr[2] = "arg2"
arr[3] = "arg3"
arr[4] = "arg4"
echo $fn(5, unsafeAddr arr)


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the C library works _correctly_ and the logs show good results while the nim 
program will output garbage.

Creating C array

[trtt]

Hi

> How to create and pass an array of string to nim and pass it to C?


type CArray{.unchecked.}[T] = array[0..0, T]#found it on the forum

proc fn(argc: cint, args: ptr CArray[cstring]): cstring {.importc, dynlib: 
"...".}


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I tried this but got *** stack smashing detected ***:  terminated:


proc fn*(elems: seq[string]): string =
  var arr: CArray[cstring]
  arr[0] = "start"
  var i = 1
  for elem in elems:
arr[i] = elem
i += 1
  var size: cint = cast[cint](elems.len() + 1)
  return $kget(size, addr arr)# tried it with unsafeAddr too


Run