In the following code, the compiler complains as: struct std::array<double,5ul> has no member named 'assign'. Here, it seems possible. Why is it so? (Compiler: g++ 4.8.2)
#include <array>
int main()
{
std::array<double,5> arr;
arr.assign(4.); // error: has no member named 'assign'
return 0;
}
array::assign() is a Visual Studio extension. You are compiling with g++. Check here standard g++ array
As already mentioned, there simply is no assign member to std::array.
The interesting question now becomes why ? After all, the other containers have an assign member method !
I would note that unlike other containers, std::array has a fixed size. If you use std::vector<T>::assign (which would be a close equivalent), the vector is resized appropriately to match the size of the sequence being assigned; with an array, however, that would be impossible:
this would be counter-intuitive, as the question does not arise for the other containers since their size is just adapted on the fly.
For a similar reason, std::array does not have: reserve, capacity, clear, insert, emplace, erase, push/pop (and variants) or resize. All of them suppose a container which size may vary.
fill_n to set all elements to the input argument.std::array::fill for that.That is very simple, as you can see here there is no assign member function for an std array. There is however a member function called fill you should be able to use.
The assign method it is not a member of std::array. The member fill does what the assign did in TR1.
assign was originally part of std::tr1::array (from the TR1) and was changed to be fill circa the C++0x (now C++11) draft n2798 (2008).
This is not really a Microsoft extension, I would imagine that they have probably maintained this method for compatibility with, and support for tr1 implementations in production (the method implementations are exactly the same).
std::arrayhas noassignmember function?