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
11
votes
5 answers
fill std::array in the member initialization list
The following code works but I would like to avoid the warning:
warning: 'fitness::vect_' should be initialized in the
member initialization list [-Weffc++]
when it is compiled with the g++ -Weffc++ switch:
#include
template
manlio
- 18,345
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11
votes
4 answers
Array declaration and initialization in C++11
Here are 8 ways to declare and initialize arrays in C++11 that seems ok under g++:
/*0*/ std::array arr0({1, 2, 3});
/*1*/ std::array arr1({{1, 2, 3}});
/*2*/ std::array arr2{1, 2, 3};
/*3*/ std::array arr3{{1, 2,…
Vincent
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10
votes
1 answer
std class specialization - meeting the standard library requirements for the original std::array template
In Is it safe to define a specialization for std::array the questioner asks if it's safe to specialize std::array for a program defined type which has an expensive default constructor. The goal is to instead initialize all elements in the std::array…
Ted Lyngmo
- 93,841
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- 108
10
votes
4 answers
Compile time size of data member std::array in non-class template (C++14)
Compile-time inspection std::array data member for its (compile time) size
I need to statically assert that the compile-time size of a non-constexpr data member of type std::array, say arr_, of a non-template class is equal to a given (externally…
dfrib
- 70,367
- 12
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- 192
10
votes
3 answers
C++ performance std::array vs std::vector
I know C-style arrays or std::array aren't faster than vectors. I use vectors all the time (and I use them well). However, I have some situation in which the use of std::array performs better than with std::vector, and I have no clue why (tested…
mfnx
- 2,894
- 1
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- 28
10
votes
1 answer
Multiplying each element of an std::array at compile time
I would like to convert an std::array to another std::array, multiplying each of its elements by a specific number.
What I have right now obviously doesn't work:
#include
#include
#include
template
syntagma
- 23,346
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- 134
10
votes
1 answer
constexpr std::array with static_assert
#include
#include
int main(int argc, char **argv) {
constexpr const std::array arr {{ 0, 1 }};
constexpr const int arr2[] = { 0, 1};
static_assert(arr[0] == arr2[0], "asdf");
static_assert(arr[1] ==…
inetknght
- 4,300
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10
votes
2 answers
How does std::array initializer work for char's?
I'm not sure how the following code works. I thought you had to do {'h', 'e' ...etc...} but it seems to work fine. On the other hand if you do std::array
user4051846
- 103
- 1
- 5
10
votes
1 answer
Initializing std::array member in constructor using string literal. GCC bug?
The following example initializing a std::array member in a constructor using a string literal doesn't compile on GCC 4.8 but compiles using Clang 3.4.
#include
#include
struct A {
std::array x;
…
Ricky65
- 1,657
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9
votes
1 answer
Why can't a 2D std::array be initialized with two layers of list-initializers?
can someone help me understand why my compiler can't/doesn't deduce this? (using g++ 7.3)
Does not work:
#include
std::array,2> f() {
return {{0,0},{0,0}};
}
Works fine:
#include…
Peter Mitrano
- 2,132
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- 31
9
votes
2 answers
Initializing private std::array member in the constructor
I was wondering what is the proper way to initialize a std::array member of the class in the constructor, when the initial array values are parameters to the constructor?
More specifically, consider the following example:
class Car {
public:
…
MikeL
- 2,369
- 2
- 24
- 38
9
votes
4 answers
Why can't I decrement std::array::end()?
I'm creating a convenient display() function template for container types. The output for the last element is different from the rest, thus I check when myIterator != --cont.cend();. This works for std::vector, but won't work for std::array.…
Jersey
- 423
- 4
- 13
9
votes
6 answers
Simplest way to get memory size of std::array's underlying array?
Is this the simplest/shortest way to get size in memory of the content of what std::array::data() returns?
arr.size() * sizeof(arr.value_type)
Edit: My question wasn't precise. By "size in memory" I mean size of all elements (themselves) contained…
NPS
- 6,003
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9
votes
2 answers
initialize std::array without copying/moving elements
#include
#include
#include
class C {
private:
std::string a;
std::string b;
std::string c;
public:
C(std::string a_, std::string b_, std::string c_) : a{a_},b{b_},c{c_} {}
~C(){};
C(const C&)…
Marinos K
- 1,779
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- 39
9
votes
4 answers
How do you declare a pointer to a C++11 std::array?
Depending on a variable, I need to select the SeedPositions32 or SeedPositions16 array for further use. I thought a pointer would allow this but I can't seed to make it work. How do you declare a pointer to a C++11 std::array? I tried the…
whitebloodcell
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