Reputation: 331

Reverse String Program

I have written a short String reverse program in C++. I decided to write it in Java, and so I did. However, once I completed writing the program, I encountered several errors that I have tried to fix but cannot fix. One of the errors was an ArrayOutOfBounds exception. Please help me fix the errors. The C++ program worked fine. Below is the Java code. Please note that I do not want to use inbuilt functions.

import java.util.Scanner;

public class Main{
    public static void main(String[] args){
      Scanner scan = new Scanner(System.in);
      String word;
      int i = 0;
      boolean inp = true;
      System.out.println("Enter one or more words to be reversed:");
      word = scan.nextLine();
      char wordArray[] = word.toCharArray();
      while(wordArray[i]!='\0')
          i++;
      while(inp == true){
          i--;
          System.out.println(wordArray[i]);
          if(i==0){
              System.out.println();
              break;
          }
        }
     }
  }

Upvotes: 0

Answers (4)

Óscar López

Reputation: 236140

This is another possibility, perhaps simpler:

public String reverse(String str) {
    char[] chars = str.toCharArray();
    int n = chars.length;
    for (int i = 0; i < n/2; i++) {
        char tmp = chars[i];
        chars[i] = chars[n-i-1];
        chars[n-i-1] = tmp;
    }
    return new String(chars);
}

And although you mentioned that you don't want to use built-in functions, the most idiomatic way would be this:

public String reverse(String str) {
    return new StringBuilder(str).reverse().toString();
}

Upvotes: 3

Yogu

Reputation: 9455

Java Strings are not zero-terminated, thus the byte array created from string isn't either. You used a loop to determine the length of your array, but that loop doesn't find a byte with value 0, so it goes over the range. Use word.length() instead.

The second thing: You used System.out.println to print the character - that inserts a linebreak after each character. Is this intended?

Upvotes: 0