what is the output of this code and why??

Question

void fun(int *ptr)
{*ptr=30;}
int main(){
int y=20;
fun(&y);
printf("%d",y);
return 0;}

https://code.sololearn.com/cu35vsqJl483

Answer 1

Line 5 passes the address of variable y to function fun
Line 2 changes the contents of this address to 30
The contents of the address of variable y is the variable itself - so changing it changes the variable value
Line 6 prints the changed y

Answer 2

it is 30 as the compiler and sololearn site says but i m confused why the value of it is like this and not 20.

Answer 3

Main:
Hey lets save 20 in box y of our post office.(int y=20)
Hey fun my old friend, look the post office, i put something in the green box(fun(&y))
Fun: Cool box, whatever was in there before, lets change it to 30 packets(*ptr=30)
Main: lets count the packets in our box and shout it…”30”