CODEWITHSUNDEEP
c++c++11c++14
CaesarK
CaesarK

Reputation: 73

How to pass an array of vectors by reference?

#include <vector>
using std::vector;

int main(void)
{
    vector<int> gr[10];

    function(gr);
}

How should I define that function calling by reference rather than by value?

Upvotes: 2

Views: 8459

Answers (3)

Ron
Ron

Reputation: 15501

To pass an array of ten ints by reference you would use:

void foo(int (&gr)[10]);

Similarly, for an array of ten std::vectors it would be:

void foo(std::vector<int> (&gr)[10]);

That being said an array of vectors is somewhat unusual structure. Prefer std::array to raw arrays.

Upvotes: 4

Edgar Rokjān
Edgar Rokjān

Reputation: 17483

auto function(vector<int> (&gr)[10]) { ... }

It should be the right syntax to pass an array of std::vector<int> by reference.

Upvotes: 5

Cheers and hth. - Alf
Cheers and hth. - Alf

Reputation: 145204

For pass by reference:

void foo( vector<int> const (&v)[10] )

Or sans const if foo is going to modify the actual argument.

To avoid the problems of the inside-out original C syntax for declarations you can do this:

template< size_t n, class Item >
using raw_array_of_ = Item[n];

void bar( raw_array_of_<10, vector<int>> const& v );

However, if you had used std::array in your main function, you could do just this:

void better( std::array<vector<int>, 10> const& v );

But this function doesn't accept a raw array as argument, only a std::array.

Upvotes: 7

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