Mirror of forum.nim-lang.org

5345 :: Newbie question: let f = 0.0; why type(f) is float64 instead of float?

• htorun (orginal) [2019-10-13T00:26:06+02:00] view original

  This may not be a critical issue but I am trying to understand the basics well to be able to build on them. This is what I think I know:

  When we declare a variable, we declare it with a type:

  var
    i: int = 0
    i3: int8 = 1
    f: float = 0.0
    f32: float32 = 3.14
  Run

  Manual says, any integer literal without a type suffix will have the generic unsigned int type (as I understand, with a platform dependent size: 32 or 64-bit).

  Similarly, float is the generic type for floating point literals (specific to this implementation, not platform dependent, always 64-bit).

  This is probably where I am misinterpreting this but from this info, I expect the following:

  var
    i = 0    # type int
    f = 0.0  # type float
  
  doAssert $type(i) == "int"
  echo sizeof(i)  # platform dependent, 4 (32-bit) or 8 (64-bit)
  
  doAssert $type(f) == "float"  # contrary to my expectation, this FAILS
  echo sizeof(f)  # always 8 (64-bit)
  
  echo type(f)  # apparently the type of "f" is "float64"
  Run

  Am I getting this all wrong or, although most probably not that important at all, would it be better (or maybe less confusing at least for me) if type(f) was "float"?

  Thanks in advance

---

• juancarlospaco (orginal) [2019-10-13T02:16:53+02:00] view original

  doAssert f is float is the way to assert the type.

---