Lower triangular number pattern

//c++ program to display a pattern like that

//so user only has to enter size
#include <iostream>
using namespace std;
int main()
{
 int size;        //declaring variable
 cout<<"Enter size = ";     //asking for input
 cin>>size;        //giving input(size)
 if(size>0)        // applying check
 {
  for(int i=1;i<=size;i++)    //applying outer loop which will controll number of rows
  {
   for(int j=1;j<=i;j++)    //applying inner loop whiuch will controll number of columns
   {
   cout<<j<<" ";
  }
  cout<<endl;
  }
 }
 else
 {
  cout<<"You have enter wrong size\n";   //condition for invalid input
 }
 return 0;
}