CODEWITHSUNDEEP
c
user2985083
user2985083

Reputation: 59

Understanding a basic program

I'm trying to understand the code below and i'm having a hard time understanding it.
It's very basic for you but for me it's quite a bit complicated. I would really appreciate your answer.

 #include<stdio.h>
 void fun(int);
 int proc(pf, int, int);

int main()
{
  int a=3;
  fun(a);
  return 0;
}

void fun(int n)
{
     if(n > 0)
   {
    fun(--n);
    printf("%d,", n);
    fun(--n);
   }
}

From what I understand fun takes 3 so--> fun(3) and then it calls up the function until n is not > than 0. so it must store 3,2,1,0 right?

But yet again it prints 0 because 0 is not bigger than 0.

What I don't understand is the printf inside the if statement because we're printing if n>0 so when 0 is not bigger than 0 shouldn't it skip the statement? and return nothing?

I know what it's printing but i'm really trying to understand.

Let me know if my question was clear enough

Upvotes: 0

Views: 65

Answers (2)

Maroun
Maroun

Reputation: 96018

I hope that this will illustrate it:

            fun(3)
            ------
              ↓         
           fun(2)  print → fun(1) ..
              ↓
           fun(1)  print → fun(0)
              ↓
           fun(0)  print → fun(-1)

Upvotes: 1

user529758
user529758

Reputation:

When n is 1, control flow enters the if statement, but then n is immediately decremented (fun(--n)) so it becomes 0.

Upvotes: 2

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