Answers for "vector vector c++"

c++ vector

#include <vector>

int main() {
  std::vector<int> v;
  v.push_back(10); // v = [10];
  v.push_back(20); // v = [10, 20];
  
  v.pop_back(); // v = [10];
  v.push_back(30); // v = [10, 30];
  
  auto it = v.begin();
  int x = *it; // x = 10;
  ++it;
  int y = *it; // y = 30
  ++it;
  bool is_end = it == v.end(); // is_end = true
  
  return 0;
}

get values from a vector of vectors c++

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

int main()
{
    vector<vector<int> > buff;

    for(int i = 0; i < 10; i++)
    {
        vector<int> temp; // create an array, don't work directly on buff yet.
        for(int j = 0; j < 10; j++)
            temp.push_back(i); 
 
        buff.push_back(temp); // Store the array in the buffer
    }

    for(int i = 0; i < buff.size(); ++i)
    {
        for(int j = 0; j < buff[i].size(); ++j)
            cout << buff[i][j];
        cout << endl;
    }

    return 0;
}

vector of vectors c++

vector<vector<int>> matrix(x, vector<int>(y));

This creates x vectors of size y, filled with 0's.

vector in c++

vector<int> g1; 
  
    for (int i = 1; i <= 5; i++) 
        g1.push_back(i); 
  
    cout << "Output of begin and end: "; 
    for (auto i = g1.begin(); i != g1.end(); ++i) 
        cout << *i << " "; 
  
    cout << "nOutput of cbegin and cend: "; 
    for (auto i = g1.cbegin(); i != g1.cend(); ++i) 
        cout << *i << " "; 
  
    cout << "nOutput of rbegin and rend: "; 
    for (auto ir = g1.rbegin(); ir != g1.rend(); ++ir) 
        cout << *ir << " ";

vector of vectors c++

vector<vector<data_type>> vec;