Why the output is 6? How do the for loops affect the value of z?

Question

#include <iostream>
using namespace std;

int main() {
int z=0;
for(int x=0; x<2; x++){
for(int y=0; y<3; y++)
++z;
}
cout<<z;
return 0;
}

Answer 1

It's called the loop nesting....The 2nd loop is controlled by the 1st loop.. 1st time when the x's value was 0 then then 2nd loop iterated 3 times so that the value of z becomes 3...After that, the 1st loop runs one more time and 2nd loop iterated again so the value of z become 6 and now the condition of 1st loop is false..... so the result is z equal to 6.

Answer 2

First executed loop is x = 0,
x = 0,y=0, z = 1.
x = 0, y=1, z = 2.
x = 0, y=2, z = 3.
In second loop x = 1,
x = 1,y = 0, z = 4.
x = 1, y=1, z = 5.
x = 1, y = 2, z = 6.
Condition x < 2 and y < 3, and loop is ended.

Answer 3

what is 2 × 3

Answer 4

z is initialized at 0.
Each time the z++ instruction is executed, z is incremented by 1.
You have a nested loop situation here, the first loop is executed twice and inside -- another loop is executed thrice, so altogether the ++z instruction is processed 2*3 times.

That ends up with z at 6 :)