Column size and row size of a 2D vector in C++

Question

I have a vector like this :

vector< vector<int> > myVector; 

All row and column numbers are same in this vector.

I want to find row count and column count of this vector.

For row count I come up with :

myVector[0].size(); 

For column count, I can't come up with anything. Can you tell me if my row count is correct and can you tell me how I can get column count? Thanks.

Answer 1

You have a vector of integer vectors myVector[0].size() returns you the amount of elements in the first int vector in the 2d vector.

The structure of such vector looks like this:

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

#include <iostream> #include <vector>  int main(){     std::vector<std::vector<int>>MyVector;     std::vector<int>temp;      temp.push_back(1);     temp.push_back(2);     temp.push_back(3);     MyVector.push_back(temp);      std::cout << "Rows in the 2d vector: " << MyVector.size() <<     std::endl << "Collumns in the 1st row: " << MyVector[0].size() <<     std::endl;      system("pause");     return 0; } 

This is the output:

Rows in the 2d vector: 1 Collumns in the 1st row: 3 

Answer 2

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

Here v is a two dimensional vector of varying size in terms of column size. Use v.size() as it gives the total number of rows and v[i].size() gives you the total number of colums in ith row. The following code can be used to iterate through varying two dimensional vector.