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51 :: Pointers used as arrays

• Schala (orginal) [2012-07-04T01:37:22+02:00] view original

  In C pointers are able to be used as arrays like this

  void foo(int* data) {
    for(int i = 0; i < 4; i++)
      data[i] = 0;
  }
  Run

  However, trying to do something equivalent in Nimrod yields a type mismatch error:

  var
    data: array[0..8, int]
  
  proc print(da: pointer) =
    for i in countup(0, 8):
      echo($da[i])
  Run

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• leledumbo (orginal) [2012-07-04T06:34:21+02:00] view original

  In short: Nimrod is NOT C, so don't use any C idiom in Nimrod (except when it's the same). In this case, pointer is a distinct type from array. What do you actually want to do? If creating a function that accepts an array of variable number of elements, use sequence. Arrays can be converted into sequence just by prepending it with @. See: http://nimrod-code.org/tut1.html#sequences

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• Araq (orginal) [2012-07-04T23:28:59+02:00] view original

  Interfacing with C arrays is a bit cumbersome. This prototype:

  void vector_add(int* a, int* b, int n);
  Run

  Can be accessed with:

  
  proc vector_add(a, b: ptr cint, n: cint) {.importc, cdecl.}
  
  template `:-/`(x: expr): expr = cast[ptr type(x[0])](addr x)
  
  var x, y: array[0..10, cint]
  
  vector_add( :-/x,  :-/y, x.len)
  Run

  PS: Couldn't resist the temptation to show off some of Nimrod's features.

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• Schala (orginal) [2012-07-04T23:48:44+02:00] view original

  Hehe, what better template symbol to use than the uncertain face.

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