Jumping straight to code, this is what I would like to do:
size_t len = obj->someLengthFunctionThatReturnsTypeSizeT();
array<int>^ a = gcnew array<int>(len);
When I try this, I get the error
conversion from size_t to int, possible loss of data
Is there a way I can get this code to compile without explicitly casting to int? I find it odd that I can't initialize an array to this size, especially because there is a LongLength property (and how could you get a length as a long - bigger than int - if you can only initialize a length as an int?).
Thanks!
P.S.: I did find this article that says that it may be impractical to allocate an array that is truly size_t, but I don't think that is a concern. The point is that the length I would like to initialize to is stored in a size_t variable.
Managed arrays are implemented for using Int32 as indices, there is no way around that. You cannot allocate arrays larger than Int32.MaxValue.
You could use the static method Array::CreateInstance (the overload that takes a Type and an array of Int64), and then cast the resulting System::Array to the appropriate actual array type (e.g. array<int>^). Note that the passed values must not be larger than Int32.MaxValue. And you would still need to cast.
So you have at least two options. Either casting:
// Would truncate the value if it is too large
array<int>^ a = gcnew array<int>((int)len);
or this (no need to cast len, but the result of CreateInstance):
// Throws an ArgumentOutOfRangeException if len is too large
array<int>^ a = (array<int>^)Array::CreateInstance(int::typeid, len);
Personally, i find the first better. You still might want to check the actual size of len so that you don't run into any of the mentioned errors.