CODEWITHSUNDEEP
javastringalgorithm
photosynthesis
photosynthesis

Reputation: 2890

How to handle special characters like "\n" in string reverse?

I have the following code to reverse a string, and I am considering to make test cases for it. I would like to know how to handle cases like when user input "\n", "\t" ?

private static String reverse2(String str) {
    if (str == null || str.length() == 0)
        return str;

    int start = 0;
    int end = str.length() - 1;

    char[] chars = str.toCharArray();
    while (start < end) {
        char tmp = chars[start];
        chars[start] = chars[end];
        chars[end] = tmp;

        start++;
        end--;
    }

    return String.valueOf(chars);
}

Upvotes: 2

Views: 1598

Answers (4)

mohit kumar
mohit kumar

Reputation: 179

In strings like "\nxyz", str.toCharArray() treats "\n" as a single character. There is no issue in your code. Only thing place of new line char will change and it will print in different line format this time.

Upvotes: 4

user1196549
user1196549

Reputation:

Your question is ambiguous and the answer not so simple.

If what you call user input is a Java literal string like "newline -\n-", the sequence \n is turned into a single newline character. When you print the string, you don't see the \n anymore. Instead, further output goes to the next line, giving

newline -
-

(11 characters). Reversal gives

-
- enilwen

On the opposite, if user input is from the keyboard, the escapes will not be recognized and a print will output the string unchanged.

newline -\n-

(12 characters). Reversal gives

-n\- enilwen

If you want the escapes to be recognized and translated, you need to do that yourself by checking every input character.

In the weirdest of the cases, you can restore the escapes after reversal (so that they become visible again), giving the transforms

newline -\n-

(12 characters) then internally,

newline -
-

(11 characters) then internally reversed, 

-
- enilwen

(11 characters) then externally

-\n- enilwen

(12 characters). Notice the difference with above n\ vs \n.

Upvotes: 2

Mikael Engver
Mikael Engver

Reputation: 4768

Why not reverse it using a StringBuilder:

string input = "xyz\t\nabc123";
string reversed = new StringBuilder(input).reverse().toString();

Upvotes: 3

Sanjay Rabari
Sanjay Rabari

Reputation: 2081

 StringBuilder str = new StringBuilder("Java");

    // reverse characters of the StringBuilder and prints it

    System.out.println("reverse = " + str.reverse());

Upvotes: 4

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