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
15
votes
1 answer
Initialisation of std::array<>
Consider the following code:
#include
struct A
{
int a;
int b;
};
static std::array x1 =
{
{ 1, 2 },
{ 3, 4 },
{ 5, 6 },
{ 7, 8 }
};
static std::array x2 =
{
{
{ 1, 2 },
…
Jeremy
- 5,055
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14
votes
0 answers
why does creating a 2D array with C++ std::array require an extra pair of {}
To create a 2D array with std::vector, you'd do
vector> array2d = {{1, 2, 3, 4},
{5, 6, 7, 8},
{9, 10, 11, 12}};
The outer {} represent the outer vector; the inner {},…
codepro
- 283
- 3
- 8
14
votes
3 answers
Declaring 2 (or even multi-) dimensional std::arrays elegantly
I'm using 2-dimensional arrays based on std::array.
Basically instead of:
MyType myarray[X_SIZE][Y_SIZE];
I have:
std::array, X_SIZE> myarray;
This works perfectly fine but IMO the declaration is not very readable.
Is…
Jabberwocky
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13
votes
2 answers
No error for negative-size array
Why don't I get an error trying to create a negative-size array?
#include
int main()
{
std::array arr;
}
With -D_GLIBCXX_DEBUG -D_GLIBCXX_DEBUG_PEDANTIC I get no error. Is this intended behavior?
user6348851
- 139
- 1
- 3
13
votes
3 answers
Extract range of elements from char array into string
I want to extract a range of elements from the beginning of a char array and put them into a string. The range may be less than or equal to the number of elements.
This is what I have come up with.
// buffer is a std::array
std::string…
ksl
- 4,519
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- 106
13
votes
1 answer
What is the use of 0-length array (or std::array)?
In C++11 it allows you to create a 0 length C array and std:array like this:
int arr1[0];
std::array arr2;
So I'm thinking what is the use of a array that doesn't have a space to store?
Secondly what is the zero length array? If it is a…
Nayana Adassuriya
- 23,596
- 30
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- 147
13
votes
1 answer
What is the sizeof std::array?
What does the C++ standard say about what sizeof(std::array) should be (for some constant N)?
In a comment to a different question, it was mentioned that std::array is not always "stack allocated". The comment was in response to a different…
jxh
- 69,070
- 8
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12
votes
1 answer
std::to_array for multi dimensional array
C++20 added std::to_array so you can easily create std::array from a C-Style array, for example:
template
void foo(const T (&a)[N]) {
auto arr = std::to_array(a);
}
But, std::to_array does not support two-dimensional…
Amir Kirsh
- 12,564
- 41
- 74
12
votes
5 answers
Example where std::array::max_size and std::array::size gives different result
Whenever I try with max_size() and size() funtion of std::array, I get same results, I wanted to know if there could be a situation where two of them give different results.
user1718009
- 303
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- 7
12
votes
1 answer
Initializing an std::array of non-default-constructible elements?
Suppose type foo_t with a named constructor idiom, make_foo(). Now, I want to have exactly 123 foo's - no more, no less. So, I'm thinking about an std::array. Now, if foo_t were default-constructible, I would write:
std::array
einpoklum
- 118,144
- 57
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- 684
12
votes
3 answers
Why isn't the operator[] of a std::array temporary constexpr?
I was stuffing some values into a constexpr std::array and then continuing the compile-time static goodness into more constexpr values when I discovered that you can't use an element as a constexpr initializer in C++11.
This is because…
Xo Wang
- 377
- 1
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- 9
12
votes
4 answers
In C++, how to iterate array in reverse using for_each?
In C++11, using lambda/for_each, how do we iterate an array from end?
I tried the following, but both result in infinite loop:
for_each (end(A), begin(A), [](int i) {
....
});
for_each (A.rend(), A.rbegin(), [](int i) {
...
});
Any idea?…
user350954
- 329
- 2
- 3
- 11
11
votes
1 answer
Is the address of a std::array guaranteed the same as its data?
std::array is ... (quoting from cppreference):
This container is an aggregate type with the same semantics as a struct holding a C-style array T[N] as its only non-static data member.
Does that imply that the address of an array is always the same…
463035818_is_not_an_ai
- 109,796
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11
votes
1 answer
Fixed-size std::span vs std::array
C++20 includes std::span, which "describes an object that can refer to a contiguous sequence of objects with the first element of the sequence at position zero". Its interface is very close to std::array, though it supports dynamic extent as well as…
Alexey Romanov
- 167,066
- 35
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11
votes
3 answers
Is there a way to enforce full initialization of std::array
I am using std::array (N is a fixed template-variable).
#include
template
struct A{
size_t function(std::array arr){ return arr[N-1];} // just an example
};
int main(){
A<5> a;
…
alfC
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