Functions with return type returning no values

An interesting thing about a functions in C++ with a non-void return type is that if you forget to place a return statement at the end of your function the it automatically return the ""result of last arithmetic operation"" done in that function code or else a 0 in normal functions and a garbage value if the function is inside a class
For eg-:

#include <iostream>

#include<conio.h>
using namespace std;

int fun()
{
    int i = 34 ;
    int j = i + 1 ;     //no return type mentioned here still output is 35
}

int main()
{
    cout << fun();  //output is 35
    getch();
    return 0;
}

another example where the line j = i + 1 is missing


#include <iostream>

#include<conio.h>
using namespace std;

int fun()
{
    int i = 34 ;
  //  int j = i + 1 ;  
}

int main()
{
    cout << fun();   // output is 0
    getch();
    return 0;
}