How can I push_back data in a 2d vector of type int

Question

I have a vector and want to store int data in to it at run time can I store the data in a 2D vector in this manner ?

std::vector> n         


        

Answer 1

Here is one more approach.

#include 
#include 
#include 
#include 

int main() 
{
    std::vector > normal;
    normal.resize( 10, std::vector( 20 ) );

    for ( auto &v : normal ) std::iota( v.begin(), v.end(), 0 );

    for ( const auto &v : normal )
    {
        for ( int x : v ) std::cout << std::setw( 2 ) << x << ' ';
        std::cout << std::endl;
    }
}

The program output is

 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 
 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 
 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 
 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 
 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 
 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 
 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 
 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 
 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 
 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 

You can write a corresponding function

#include 
#include 
#include 
#include 

template 
T & init_2d( T &container, size_t m, size_t n )
{
    container.resize( m, typename T::value_type( n ) );

    for ( auto &item : container ) std::iota( item.begin(), item.end(), 0 );

    return container;
}

int main() 
{
    std::vector> v;

    for ( const auto &v : init_2d( v, 10, 20 ) )
    {
        for ( int x : v ) std::cout << std::setw( 2 ) << x << ' ';
        std::cout << std::endl;
    }

}