std::array is a container that encapsulates constant size arrays in C++.
std::array is a part of the C++ Standard Library since C++11.
Reference: https://en.cppreference.com/w/cpp/container/array
Questions tagged [stdarray]
433 questions
8
votes
1 answer
The deduction guide for std::array
In the C++ 17 and C++ 20 Working Drafts of the C++ Standard the deduction guide for the class template std::array is defined the following way
template
array(T, U...) -> array;
As a result for example this…
Vlad from Moscow
- 301,070
- 26
- 186
- 335
8
votes
1 answer
Why is size_type in std::array size_t and in std::vector usually size_t?
The documentation says, that size_type of std::vector is /usually/ size_t, which is reasonable, since an implementation can choose to use different.
But why is size_type = size_t in std::array. Especially here, as std::array is used on small µC a…
wimalopaan
- 4,838
- 1
- 21
- 39
8
votes
3 answers
Can C++ raise an error when std array initialization is too small?
Suppose I have an array of:
std::array {4,3,2};
Is it possible to raise an error or warning when this is the case? In some cases it might be useful to have this explicitly matching.
Marnix
- 6,384
- 4
- 43
- 78
8
votes
0 answers
Why does gcc take over 17 minutes to compile std::array?
Why does std::array a = {}; take more than 17 minutes to compile with gcc using -O3 on a Core i7 9700K processor?
I've stumbled on a problem with gcc where I've empty-initialized a std::array with std::strings in the header file,…
Ingemar
- 109
- 2
8
votes
2 answers
Is it possible to move an std::array into a std::vector?
This is a question about the interaction of stack memory and heap memory and the particular case of going from stack to heap via the std::array and std::vector classes.
In principle std::array can be seen as a pointer to the first elements, plus…
alfC
- 14,261
- 4
- 67
- 118
8
votes
2 answers
std::array of size zero
What does it mean to have std::array,array of size zero?
I have gone through similar questions in SO before posting this, and all those
questions are regarding simple array type and for C language and most of them says that it is illegal. But…
Sreeraj Chundayil
- 5,548
- 3
- 29
- 68
8
votes
3 answers
Class with private constructor and static array of itself
Sorry if title is confusing, I couldn't find an easy way to write it in a simple sentence. Anyways, the issue I'm facing:
// header:
class SomeThing
{
private:
SomeThing() {} // <- so users of this class can't come up
// …
Gábor Buella
- 1,840
- 14
- 22
8
votes
2 answers
Converting std::array to std::vector
In the code below, the size of the function (foo) argument (std::vector) can be anything to make the function a generic one. However, sometimes the size container is known so std::array can be used. The problem is to convert the std::array to…
Shibli
- 5,879
- 13
- 62
- 126
7
votes
4 answers
What is the difference between [start/2 + mid/2] and [(start + mid)/2] in binary search?
In the binary search algorithm, we set the mid as:
mid = (start + end)/2 which is same as
mid = start/2 + end/2 and also equal to
mid = start + (end - start)/2
but all of the three give different results being the same arithmetic expression.
How…
user19117411
- 105
- 5
7
votes
1 answer
Is it possible to emplace a std::array in a container? If it is how? If not, why?
Given the simple code
#include
#include
int main() {
std::vector> v;
v.emplace_back(std::array{1,2,3});
}
I'm first of all worried about what is really going on.
My understanding of emplace_back is…
Enlico
- 23,259
- 6
- 48
- 102
7
votes
2 answers
Size of reference to std::array not available at compiletime
I'm interested to know why the second static_assert in my code below doesn't work. It seems like even though the array c is a reference to a, the size of the array is embedded in the type, so it should be available at compile time.
#include…
Jacob Merson
- 130
- 5
7
votes
3 answers
In C++ what is the point of std::array if the size has to be determined at compile time?
Pardon my ignorance, it appears to me that std::array is meant to be an STL replacement for your regular arrays. But because the array size has to be passed as a template parameter, it prevents us from creating std::array with a size known only at…
Plasty Grove
- 2,807
- 5
- 31
- 42
7
votes
1 answer
how convert std::array to char (&dest)[N]?
What is the way to pass std::array to
such function:
template
void safe_func(char (&dest)[N]);
?
I try this one:
#include
template using SafeArray = char[N];
template void safe_func(char…
user1244932
- 7,352
- 5
- 46
- 103
7
votes
2 answers
Why are "double braces" needed in declaration of multi-dimensional array using stacked std::array?
#include
using std::array;
constexpr auto d1=2;
constexpr auto d2=3;
constexpr auto d3=4;
// stacked std::array
using arr_t = array;
using arr2d_t = array;
using arr3d_t = array;
constexpr arr3d_t arr1 = {{
…
sandthorn
- 2,770
- 1
- 15
- 59
7
votes
2 answers
Why isn't std::array's operator==() marked constexpr?
It's very natural to want to compare std::array's at compile time; and its operator==() is obviously constexpr'able. Yet - it isn't marked constexpr. Is this intentional or an oversight? And - what's the reason it was left that way (apparently in…
einpoklum
- 118,144
- 57
- 340
- 684