CODEWITHSUNDEEP
c++arrays
dukevin
dukevin

Reputation: 23178

Initializing an int array as a type argument

This code fails to compile:

  unordered_map<char, int[4]> inv = {
    { 'a', {{0,0,1,0}} } 
  }

What's the proper way to initialize this int array when passed as a type argument?

I've tried: int[], array<int,4> but they all give the error:

no instance of constructor "std::unordered_map<_Kty, _Ty, _Hasher,
_Keyeq, _Alloc>::unordered_map [with _Kty=char, _Ty=std::pair<Cell *, int []>, _Hasher=std::hash<char>, _Keyeq=std::equal_to<char>,
 _Alloc=std::allocator<std::pair<const char, std::pair<Cell *, int []>>>]" matches the argument list

Upvotes: 0

Views: 90

Answers (2)

Constantinos Glynos
Constantinos Glynos

Reputation: 3186

You can initialize the array with one set of angle brackets.

int main()
{
    std::unordered_map<char,std::array<int,4>> inv = {{ 'a', {1,2,3,4} }};

    for (auto &&i : inv)
        std::cout<< i.first << "->" <<i.second[0] <<std::endl;
}

Example: https://rextester.com/FOVMLC70132

Upvotes: 2

lubgr
lubgr

Reputation: 38267

This should work:

#include <array>

std::unordered_map<char, std::array<int, 4>> inv = {{ 'a', {{0, 0, 1, 0}} }};

Upvotes: 5

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