2d vector declaration in c++ code example

Example 1: how to make a 2d vector in c++

// Create a vector containing n 
//vectors of size m, all u=initialized with 0
vector<vector<int> > vec( n , vector<int> (m, 0));

Example 2: how to get size of 2d vector in c++

myVector[
  Vector[0, 4, 2, 5],
  Vector[1, 4, 2]
];

/*When you call for myVector[1].size() it would return 3 and [0] would return 4.

For the amount of rows (int vectors) in the 2d vector, you can just use myVector.size()

You can run this to see it in actions*/

Example 3: how to take input in 2d vector in c++

std::vector<vector<int>> d;
//std::vector<int> d;
cout<<"Enter the N number of ship and port:"<<endl;
cin>>in;
cout<<"\Enter preference etc..:\n";
for(i=0; i<in; i++){ 
cout<<"ship"<<i+1<<":"<<' ';
    for(j=0; j<in; j++){
    cin>>temp;
    d[i].push_back(temp); 
    }
}