CODEWITHSUNDEEP
c++
diana
diana

Reputation: 1

How to get the stack to work in function calls?

Does stack come into the frame in the following code? If num=5. Why am i getting the output as zero..what about the numbers from 5 to 1?

void rec(int num)
{
    cout << num << endl;
    if( num > 0 )
         return rec(num-1);
    cout << "after" << num << endl;
}

does it include the concept of stack?

Upvotes: 0

Views: 70

Answers (2)

Mats Petersson
Mats Petersson

Reputation: 129314

If you want to see the "returned value", you could do something like this:

void rec(int num)
{
    cout << num << endl;
    if( num > 0 )
         rec(num-1);
    cout << "after" << num << endl;
}

The return rec(num-1); is technically valid, but since the function doesn't actually return soemthing, it's the same as writing:

if (num > 0) 
{
    rec(num-1);
    return;
}

Upvotes: 0

Ran Eldan
Ran Eldan

Reputation: 1350

"Why am i getting the output as zero"

Look at the logic of you function. if(num>0) - return rec(num-1);.
So for every nubmer above 0, the function will just call itself again with num-1.
And only when num==0 you will get to this line

cout<<"after"<<num<<endl;

Meaning that for every number you will enter, the function will do nothing and call itself again with number-1 before the cout<<"after"<<num<<endl; line, and at the last time it will not call it self again (since num > 0 condition is false) and it will print 0.

Upvotes: 1

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