StackOverflow Error in program and I cant find the reason

Question

void recur(int i)
{
    if(i==n)
        return;
    String sub="";
    for(int j=i+1;j<n;j++)
    {
        sub=s.substring(i,j);
        if(isPalindrome(sub))
            System.out.println(sub);
    }
    recur(i++);
}

I am encountering a StackOverflowError at the

sub=s.substring(I,j);

statement.

s="geeks", initial value of I=0;

Where is your variable n instantiated? I think i==n returns false for all values of 'i' which is resulting in a StackOverflowError — Venkat D, Sep 02 '18 at 14:32
What is `n` ? If `i` is never `n`, this will never stop and being a recursive function, it will generate a stack overflow. — Bart Friederichs, Sep 02 '18 at 14:32
Possible duplicate of [When to use post increment and pre increment in Java](https://stackoverflow.com/questions/35390737/when-to-use-post-increment-and-pre-increment-in-java) — Patrick Parker, Sep 02 '18 at 14:42

score 1 · Answer 1 · answered Sep 02 '18 at 14:43

1

recur(i++);

The value of the expression i++ is the value of i at the current time; and afterwards you increment it.

As such, you are basically invoking:

recur(i);
i++;

And so you are just invoking recur again with the same parameter.

Try:

recur(++i);

answered Sep 02 '18 at 14:43

Andy Turner

131,952
11
151
228

this function does not compile, what is `n` between? – The Scientific Method Sep 02 '18 at 14:43

score 1 · Answer 2 · answered Sep 02 '18 at 14:47

1

Try This

public class P {

    public static final String s="geeks";

    static void recur(int i){

        int n=6;   //Size of string

        if(i==n)
            return;

        String sub="";

        for(int j=i+1;j<n;j++)
        {
            sub=s.substring(i,j);
            //Any Function
            System.out.println(sub);
        }
        recur(++i);
    }


    public static void main(String[] args) {

        P.recur(0);
    }
}

answered Sep 02 '18 at 14:47

Prabath

71
4

"`//Size of string`" isn't the size of the string 5? You wouldn't need the comment if you used `s.length()`. – Andy Turner Sep 02 '18 at 18:43
Yes you can add `s.length()`, and change the iteration to `for(int j=i+1;j<=n;j++)` – Prabath Sep 03 '18 at 01:27

StackOverflow Error in program and I cant find the reason

2 Answers2