Check out example codes for "how to get size of 2d vector in c++". It will help you in understanding the concepts better.

Code Example 1

``````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*/``````

Code Example 2

``````// Initializing 2D vector "vect" with
// values
vector<vector<int> > vect{ { 1, 2, 3 },
{ 4, 5, 6 },
{ 7, 8, 9 } };``````

Code Example 3

``````// finding size of a square matrix
myVector[0].size();``````

Code Example 4

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

Code Example 5

``````#include<bits/stdc++.h>
using namespace std;

int main(){
int n = 3;
int m = 4;

// Create a vector containing n
//vectors of size m.
vector<vector<int> > vec( n , vector<int> (m, 0));

for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++){
cout<< vec[i][j]<< " ";
}
cout<< "\n";
}

return 0;
}``````

Learn ReactJs, React Native from akashmittal.com