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Thread: String Reversal.... Not working

  1. #1
    Junior Member moodycrab3's Avatar
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    Default String Reversal.... Not working

    class jack 
    {
    public static String reverseString(String s, String result,int l)
    {
    if(l>=0)
    { result=result+s.charAt(l);
    reverseString(s,result,l-1);
    return result;}
    else 
    return "error";
     
    }
    public static void main(String args[])
    {
    String s="Allen downey";
    String result="";
    int l=s.length();
    String backward=reverseString(s,result,l);
    System.out.println(backward);
    }
    }
    This program should reverse the string
    But The program is not yielding output... I know what you are thinking.... why can't I just use while or for... But I can't... I am supposed to be able to write the program without any iteration...
    please help...


  2. #2
    Member DanBrown's Avatar
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    Thumbs up Re: String Reversal.... Not working

    class jack
    {
    public static String reverseString(String s, String result,int l)
    {
    if(l>=0)
    { result=result+s.charAt(l);
    reverseString(s,result,l-1);
    return result;}
    else
    return "error";

    }
    public static void main(String args[])
    {
    String s="Allen downey";
    String result="";
    int l=s.length();
    String backward=reverseString(s,result,l);
    System.out.println(backward);
    }
    }

    In the above code certain changes are required

    String backward=reverseString(s,result,l);
    Firstly length you are passing should be one less than the actual length because you are directly using length as index value , but here index in a string or array starts from 0 .

    String backward=reverseString(s,result,l);
    String backward=reverseString(s,result,l-1);

    Secondly little modification in this part , while returning value

    if(l>=0)
    { result=result+s.charAt(l);
    reverseString(s,result,l-1);
    return result;}
    else
    return "error";

    change required
    if(l>=0)
    {
    result=result+s.charAt(l);
    return reverseString(s,result,l-1);
    }
    else
    return result;
    Thanks and Regards
    Dan Brown

    Common Java Mistakes

  3. The Following User Says Thank You to DanBrown For This Useful Post:

    moodycrab3 (February 7th, 2011)

  4. #3
    Junior Member moodycrab3's Avatar
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    Default Re: String Reversal.... Not working

    OH MY GOD... u are a genius... Thank you so much... I have been trying to figure this out since yesterday... Thank you so very much....

    thank you
    thank you

  5. #4
    Member DanBrown's Avatar
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    Default Re: String Reversal.... Not working

    OH MY GOD... u are a genius... Thank you so much... I have been trying to figure this out since yesterday... Thank you so very much....

    thank you
    thank you

    you r welcome , and please mark this thread as solved.
    Thanks and Regards
    Dan Brown

    Common Java Mistakes

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