How to define a vector of two dimensional array?

Question

How to define a vector that will contain two-dimensional arrays.

eg: vector<array[16][16]> vec; // where the two dimensional array have string elements

which will contain vec ={array_1[16][16],array_2[16][16],array_3[16][16],....};

I have tried:

vector<array<array<string,16>,16>> vec;

but it does not work when I use vec.push_back(array);

error shown is:

No matching member function for call to 'push_back'

minimal code:

string arr[16][16];

vector<array<array<string,16>,16>> vec;

vec.push_back(arr);

what does `does not work.` mean? Didn't compile? What was the error message? Please provide a [mre], your code [compiles](https://godbolt.org/z/c8nEcP) — Alan Birtles, Jan 27 '21 at 17:12
@Kao if `std::array` is supported the compiler should be c++11 compliant and accept the angle brackets without spaces: https://stackoverflow.com/questions/7087033/for-nested-templates-when-did-become-standard-c-instead-of — Alan Birtles, Jan 27 '21 at 17:15
You can't name a variable like a type. You are shadowing `std::array`. You should rename it and use `std::array` instead of C-arrays: `string array[16][16];` => `array,16> arr;` — Thomas Sablik, Jan 27 '21 at 17:19
@AdithyaShetty I guess yes. Pay attention to the name of the variable, not `array` — Damien, Jan 27 '21 at 17:21

Thomas Sablik · Accepted Answer · 2021-01-27T17:51:57.827

2

You shouldn't name a variable like a type. You are shadowing std::array. You should rename the variable and use std::array instead of C-arrays:

#include <array>
#include <string>
#include <vector>

using StrArr2D = std::array<std::array<std::string, 16>, 16>;

int main() {
    StrArr2D arr;
    std::vector<StrArr2D> vec;
    vec.push_back(arr);
}

You can keep the variable name array if you avoid using namespace std; and use full qualified names.

edited Jan 27 '21 at 17:51

answered Jan 27 '21 at 17:24

Thomas Sablik

16,127
7
34
62

i am getting a as error `Implicit instantiation of undefined template 'std::array, std::allocator>, 16>, 16>'` when I tried the above – Adithya Shetty Jan 27 '21 at 17:26
1

Why not just use `arr` as the variable name? Like you use `vec` for the `vector` variable. Then you don't have to worry about the `using namespace std` issue. – Remy Lebeau Jan 27 '21 at 17:41
@RemyLebeau The variable name was `array` earlier. I wanted to show different ways. But now, after OP changed the code in the question, it makes no sense to call the array `array`. – Thomas Sablik Jan 27 '21 at 17:43
1

@ThomasSablik In your example, I would add a `using` declaration to make the code earlier to read, eg: `using StrArr2D = std::array, 16>; StrArr2D arr; std::vector vec; ...` – Remy Lebeau Jan 27 '21 at 17:49

How to define a vector of two dimensional array?

1 Answers1