Vector of Vectors in C++

In this C++ tutorial, you shall learn about vector of vectors, how to create vector of vectors, and traverse the inner vectors using For loop, with example programs.

Vector of Vectors in C++

Vector of vectors is a vector in which each element is a vector of elements.

To create a vector of vectors, we need to specify the datatype of element as vector<>, and specify vectors as elements, as shown in the following.

//int vectors
vector<int> v1 { 1, 3, 5, 7, 9 };
vector<int> v2 { 2, 4, 6, 8, 10 };

//vector of vectors
vector<vector<int>> vv = {v1, v2};

Examples

1. Vector of Integer Vectors

In the following program, we take two integer vectors in v1 and v2, and use them to create a vector of integer vectors vv.

main.cpp

#include <iostream>
#include <vector>
using namespace std;

int main() {
   //int vectors
   vector<int> v1 { 1, 3, 5, 7, 9 };
   vector<int> v2 { 2, 4, 6, 8, 10 };

   //vector of vectors
   vector<vector<int>> vv = {v1, v2};
   
   //iterate over vector elements
   for (auto& tempVector : vv) {
      for (auto& element : tempVector) {
         cout << element << "  ";
      }
      cout << endl;
   }
}

Output

1  3  5  7  9  
2  4  6  8  10

Conclusion

In this C++ Tutorial, we learned how to define a vector of vectors, and how to traverse through individual elements of the inner vectors.