A task from a challenge

Question

Hi everyone.
Can anybody explain me how does the following code work, because i don't understand the result of it.

#include <iostream>
using namespace std;

int main(){

for(int i=0;i<3;i++)
for(int j=0;j<=i;j++)
cout<<i<<endl;
return 0;
}
// Output is 011222, shouldn`t it be 012, because we ouput only i and how it becomes 011222?

Answer 1

i = 0, j <= 0 means 0 will be printed once (for j = 0).
i = 1, j <= 1 means 1 will be printed twice (for j = 0, 1).
i = 2, j <= 2 means 2 will be printed thrice (for j = 0, 1, 2).