how to reverse a string with out using charAt()

Question

how to reverse a string without using inbuilt functions not even charAt() ? I was asked this at an interview and cannot find the solution.

I'm sure he didn't mean to use string buffer , he specifically said no inbuilt functions at all, not even CharAt().

the language is java

if u did the home work it would be great if u share the solution — user3709712, Sep 18 '14 at 09:55
if you got answer of this question, please let me know. I am really curios about the solution. As far as I know, do not using any of inbuilt method, it is impossible to do anything — Juneyoung Oh, Sep 18 '14 at 11:04
yes juneyoung may be point was to point out this only ..that it cannot be done — user3709712, Sep 19 '14 at 11:12

score 1 · Answer 1 · edited May 23 '17 at 12:00

1

how to reverse a string without using inbuilt functions not even

By using the algorithm reverse? I'm assuming c++ here.

#include <iostream>
#include <string>
#include <algorithm>
using namespace std;


int main() {
    string s  = "Hallo";

    reverse( s.begin(), s.end() );
    cout << s << endl;
    return 0;
}

Prints "ollaH"

If you're language is JavaScript, it also seems to have a reverse method on arrays...

The OP indicated that he is using java, in that case this item holds the answer you're looking for:

edited May 23 '17 at 12:00

Community

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answered Sep 18 '14 at 09:22

Werner Erasmus

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no inbuilt functions means u cannot use begin or end and i'm using java – user3709712 Sep 18 '14 at 09:57
See my modified answer. – Werner Erasmus Sep 18 '14 at 13:08

score 1 · Answer 2 · answered Sep 18 '14 at 10:03

1

you can reverse String via byte Array.

note that if you use another character, you should specify char-set as a parameter of getBytes(String).

Here is my solution >>

public class Main {
    public static void main(String[] args) {
        String string = "String";
        byte[] byteArr = string.getBytes();
        byte[] secondByteArr = new byte[byteArr.length];

        for(int i = 0; i < byteArr.length ; i++){
            secondByteArr[(byteArr.length - 1) - i] = byteArr[i];
        }

        System.out.println(new String(secondByteArr));
    }
}

good luck with that:D

answered Sep 18 '14 at 10:03

Juneyoung Oh

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but then getBytes is also and inbuilt function ? – user3709712 Sep 18 '14 at 10:19
However, if you do not want to inbuilt method, you should not use types like string also. it is a part of String Object. – Juneyoung Oh Sep 18 '14 at 10:52

score 0 · Answer 3 · answered Sep 19 '14 at 10:34

0

I guess you can transform it to CharArray and reverse it from top-down for loop

String s = "abcdef";
char c[] = s.toCharArray();

for( int i = c.length -1; i>=0; i--)
    System.out.print(c[i]);

answered Sep 19 '14 at 10:34

Sayat Satybald

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how to reverse a string with out using charAt()

3 Answers3