Using for loops, how to reverse a string?

Question

This code isn't working. Can you tell me what's wrong and why?

package exer0403e08;


public class EXER0403E08 {
    public static void main(String[] args) {
        String str= "hello";
        System.out.println(str);
        char[]strchar = str.toCharArray();
        int first;
        int last=5;

        System.out.println("The reversed is: ");
        for (first=1; first<=5; first++){
            strchar[first]=strchar[last];


            last--;

        } 
        str=String.valueOf(strchar);
        str=str.toUpperCase();
        System.out.println(str);


    }

}

The answer is "OLLO" and i want to make it "OLLEH".

@h.harry Java :) I am just wondering that you wrote the program without knowing the language name you used ? — Suresh Atta
– Suresh Atta, Commented Mar 12, 2017 at 10:25

Suresh Atta · Accepted Answer · 2017-03-12 10:34:05Z

1

You loop have several problems. And you misunderstood the array indexes.

You are iterating and modifying the same array. Hence the weird behaviour and indexces will start from zero for arrays.

So the fixed code will be

public static void main(String[] args) {
        String str = "hello";
        System.out.println(str);
        char[] strchar = str.toCharArray();
        int first;
        int last = 4;

        System.out.println("The reversed is: ");
        for (first = 0; first < 5; first++) {
            strchar[first] = str.charAt(last);

            last--;

        }
        str = String.valueOf(strchar);
        str = str.toUpperCase();
        System.out.println(str);

    }

Update :

Demo link http://ideone.com/GfgDZ3

edited Mar 12, 2017 at 10:34

answered Mar 12, 2017 at 10:25

Suresh Atta

122k38 gold badges206 silver badges315 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

minigeek Over a year ago

@h.harry output is correct..see changes in above code

Suresh Atta Over a year ago

Added a demo link.

h.harry Over a year ago

thank you so much. i tried it once but no changes. but in my second trial, it's like magic. by the way, what is the language used?

Suresh Atta Over a year ago

@h.harry Java dude. Java.

minigeek Over a year ago

@sᴜʀᴇsʜᴀᴛᴛᴀ i am still laughing for this😂😂 java dude java

|

Eclipse · Accepted Answer · 2017-03-12 10:46:40Z

1

you can write your own method like this:

    public static String reverse(String str)
     {
     String reversed = new String();

     for ( int j = str.length()-1; j >= 0; j-- )
         reversed += str.charAt(j);

     return reversed;
     }

and then try reverse("Hello");

answered Mar 12, 2017 at 10:46

Eclipse

1751 silver badge13 bronze badges

2 Comments

h.harry Over a year ago

that's complicated

minigeek Over a year ago

@h.harry well for your comments on other answer..s.o. is q&a site but a strict one which is why it has quality. Google for it. All the best for coding..and this ans is not complicated just index is reversed

Community · Accepted Answer · 2017-05-23 11:46:33Z

0

You have better methods in java to reverse string. Please check this answer :

You can use this:

new StringBuilder(hi).reverse().toString()

Or, for versions earlier than JDK 1.5, use java.util.StringBuffer instead of StringBuilder — they have the same API. Thanks commentators for pointing out that StringBuilder is preferred nowadays.

edited May 23, 2017 at 11:46

CommunityBot

11 silver badge

answered Mar 12, 2017 at 10:28

Arun Shankar

2,5932 gold badges28 silver badges36 bronze badges

6 Comments

Arun Shankar Over a year ago

Didn't think that SO is a tutorial site :-) And , the question didn't say he just want to learn loops :-)

h.harry Over a year ago

ok but our teacher won't accept that. he prefers using for loops only.

h.harry Over a year ago

what's the purpose of asking?

h.harry Over a year ago

can you please tell me the language used?

h.harry Over a year ago

@sᴜʀᴇsʜᴀᴛᴛᴀ what's the language used?

|

Collectives™ on Stack Overflow

Using for loops, how to reverse a string?

3 Answers 3

6 Comments

2 Comments

6 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

6 Comments

2 Comments

6 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related