recursive - simple screenshot but detail principle.

the code below demonstates the principle of the'recursive-call' that the programing beginner may be confused with,and each demonstrate was followed by a screenshot:

the first part of the code called in the main:

1 String s2 = toBinary2(6, sb);

the actual code:

1 static String toBinary2(long n, StringBuilder sb)
2     {
3         if(n > 0)
4         {
5             toBinary2(n / 2, sb);
6             sb.append(n % 2);            
7         }
8         return sb.toString();
9     }

the relevant screenshot:

figure 01 - to binary

 

the second part of the code called in the main:

1 int sum = sum(100000);

the actual code:

1 static int sum(int num)
2     {
3         if(num == 1)
4             return 1;
5         return num + sum(num - 1);
6     }

the correspond screenshot: