Assigning to a two dimensional vector in c++

Question

#include<bits/stdc++.h>
using namespace std;
main()
{
    vector<vector<int> > v;
    for(int i = 0;i < 3;i++)
    {
        vector<int> temp;
        for(int j = 0;j < 3;j++)
        {
            temp.push_back(j);
        }
        //cout<<typeid(temp).name()<<endl;
        v[i].push_back(temp);
    }
 }

I am trying to assign to a two dimensional vector. I am getting the following error

No matching function for call to 
std ::vector<int>::push_back(std::vector<int> &)

Answer 1

Problem: Your vector v is empty yet and you can't access v[i] without pushing any vector in v.

Solution: Replace the statement v[i].push_back(temp); with v.push_back(temp);

Answer 2

You can follow this process :

#include<bits/stdc++.h>
using namespace std;
int main()
{
    vector<vector<int> > v;
    for(int i = 0;i < 3;i++)
    {
        vector<int> temp;
        for(int j = 0;j < 3;j++)
        {
            temp.push_back(j);

        }
        //cout<<typeid(temp).name()<<endl;
        v.push_back(temp);
    }
    for(int i = 0; i < 3; i++){
        for(int j = 0; j < 3; j++){
            cout << v[i][j] << " ";
        }
        cout << endl;
    }
 }