CODEWITHSUNDEEP
c++classvectorinitializationstdvector
GoodDeeds
GoodDeeds

Reputation: 8497

Initializing both dimensions of a vector of vectors inside a class

I have a class

class A
{
    private:   
        std::vector< std::vector<int> > v;
    //other statements
}

I would like to initialize both dimensions of this vector by passing them to the constructor of the class, possibly using initializer lists.

This question asks about the same question for a vector of integers, and this asks about initialization of a vector of vectors, but outside any class. I want to initialize the sizes of both dimensions, but the vector is a class member.

How can I do this?

Upvotes: 2

Views: 2971

Answers (2)

Richard Hodges
Richard Hodges

Reputation: 69854

Did you want to initialise with existing data?

struct Matrix
{
    Matrix(std::initializer_list< std::initializer_list<int> > ilil)
    {
        data_.reserve(ilil.size());
        for (auto&& il : ilil)
        {
            data_.emplace_back(il);
        }
    }

    std::vector< std::vector<int> > data_;
};

void test()
{
    auto m = Matrix {
        { 1, 2, 3 },
        { 4, 5, 6 },
        { 7, 8, 9 }
    };
}

Upvotes: 2

apple apple
apple apple

Reputation: 10591

you can put them in the member initializer lists

like this

class A{
public:
   A(int dim1,int dim2):v(dim1,std::vector<int>(dim2)){}
private:   
   std::vector< std::vector<int> > v;
};

or you can use vector::resize

class A{
public:
   A(int dim1,int dim2){v.resize(dim1,std::vector<int>(dim2));}
private:   
   std::vector< std::vector<int> > v;
};

Upvotes: 5

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