How to Print Even and Odd Position Characters of an Array of Strings in Java

How to print even and odd position characters of an array of strings in Java?

int T = scan.nextInt();

This reads quantity of test cases, which we're going to process.

String string[] = new String[T];
for(int i = 0; i<T; i++){
  string[i] = scan.next();

}
Next we're creating an array named "string" (BTW, this a bad name for variables/objects) which has size T and in the for loop reading test cases from the input T times and saving them in the array.

for(int temp = 0; temp<T; temp++){

Now, for each of test cases we do the following...

for(int j = 0; j<string[temp].length(); j = j+2)
{
    System.out.print(string[temp].charAt(j));
}

We create a local variable j, which is visible only in this for loop. j holds index of the string (=string[temp]), which we're processing. So, we're printing a character on position j (by using standard method "charAt" of String class, which returns character of given index of the string) and then increasing it by 2. So, this code will print every even character. For string "example", it will print "eape" (j=0, j=2, j=4, j=6).

System.out.print(" ");

Separating sequences with a space.

for(int j = 1; j<string[temp].length(); j = j+2){
    System.out.print(string[temp].charAt(j));
}

System.out.println();

We're doing the same (creating index j, running though all characters of the string), but starting from "1", so it will print all odd characters of the string. For string "example", it will give you "xml" (j=1, j=3, j=5). and After this, it will end the string. I hope, it will help you to understand. :)

How do I print just the even or odd chars in an array?

Just a minor mistake in the code:

You don't need the first value from the array to initialize the loop variable i, just the index value you want the loop to start from.

One tricky thing to keep in mind is that the indexing starts from 0, but we, humans count from 1. _{(I did a mistake with this in the first edit of the answer too)} So the characterss with even ordinals will be printed when the start value is odd.

The start of indexing is quite a common issue one has to constantly keep in mind...

Also, you can print characters directly, you don't need the Arrays.toString() method here:

System.out.println(t[index]);

Is enough.

Odd chars: set i to 0: this will print the 1st, 3rd ... characters

       for(int i = 0; i < t.length; i = i + 2){
            System.out.println(t[i]);
        }

Even chars: set i to 1: this will print the 2nd, 4th ... chars

       for(int i = 1; i < t.length; i = i + 2){
            System.out.println(t[i]);
        }

Eliminating the array

Also, you don't even need to create a char array, you could use String.charAt(int index) for this purpose:

        String even_odd = sc.next();

        for(int i = 0; i < even_odd.length(); i = i + 2){
            System.out.println(even_odd.charAt(i));
        }

Taking it to the next level

Also, to be extra nice, you could extract this into a function, and reuse the functionality:

private static void printChars(String input, boolean even) {
        int i = 0;
        if(even) { //if we need the even chars, start from 1;
          i=1;
        }
        for(; i < input.length(); i = i + 2){
            System.out.println(input.charAt(i));
        }
}

And then your main method would be just this:

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        String even_odd = sc.next();
        char[] t = even_odd.toCharArray();
        System.out.println(Arrays.toString(t));

        //calling the function for even numbers
        printChars(even_odd, true);

        //calling the function for odd numbers
        printChars(even_odd, false);
    }

Remember duplication is bad. Reuse --> good.

Split a string in java according to characters with even or odd order

I used two strings called odd and even and set both of them to be empty then i iterate throught all the letters of the string s and add the even characters to even and odd characters to odd like the following:

String S = "alfabet";
            String odd="";String even="";
            for(int c=0;c<S.length();c++)
            {
                if(c%2==0)odd+=S.charAt(c);
                else even+=S.charAt(c);
            }

printing character at even and odd position of a multiple strings

You are restricting yourself to an archaic version of C syntax that required all local variables to be declared at the top of a block, ahead of any executable statements.

Since your code is not using variables other than count outside the do/while loop, you should move their declarations inside the loop. This will ensure that the variables have appropriate initial values at the beginning of each iteration.

Here are a few additional points to keep in mind:

• Your code will result in undefined behavior if an end-user terminates the input stream (Ctrl+Z on Windows, Ctrl+D on UNIX) without entering any characters
• Your code will drop the last character when end-user terminates input stream after entering less than ten characters
• odd[0]=even[0]='\0' is unnecessary

How to get odd and even position characters from a string?

It would probably be easier to use a regular expression and .replace: capture two characters in separate capturing groups, add the first character to a string, and replace with the second character. Then, you'll have first half of the output you need in one string, and the second in another: just concatenate them together and return:

function encrypt(text) {  let removedText = '';  const replacedText1 = text.replace(/(.)(.)?/g, (_, firstChar, secondChar) => {    // in case the match was at the end of the string,    // and the string has an odd number of characters:    if (!secondChar) secondChar = '';    // remove the firstChar from the string, while adding it to removedText:    removedText += firstChar;    return secondChar;  });  return replacedText1 + removedText;}console.log(encrypt('This is a test!'));

import java.io.*;
import java.util.*;

public class Trying4 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("Enter the number of words: ");
        int numWords = in.nextInt();
        in.nextLine(); // consume the new-line character after the number
        for(int i = 0; i < numWords; i++) {
            char[] word = in.nextLine().toCharArray();
            display(word);
        }
    }
    public static void display(char[] word) {
        for(int i = 0; i < word.length; i += 2) {
            System.out.print(word[i]);
        }
        System.out.print(" ");
        for(int i = 1; i < word.length; j += 2) {
            System.out.print(word[i]);
        }
        System.out.println();
    }
}

def f(in: String): (List[Char], List[Char]) = {
  @tailrec def run(s: String, idx: Int, accEven: List[Char], accOdd: List[Char]): (List[Char], List[Char]) = {
    if (idx < 0) (accEven, accOdd)
    else if (idx % 2 == 0) run(s, idx - 1, s.charAt(idx) :: accEven, accOdd)
    else run(s, idx - 1, accEven, s.charAt(idx) :: accOdd)
  }
  run(in, in.length - 1, Nil, Nil)
}

val (even, odd) = f("abcdefg")
println(even.mkString)

char *str[41];

char str[41];

while (str[i]) {
    if (i % 2 == 0) {
        odd[j++] = str[i];
    } else {
        even[k++] = str[i];
    }
    i++;
}

char str[41];

char *p = str;

while (*p) { // test end of string termination
    if (i % 2 == 0) {  // if ((p-str) % 2 == 0) { would allow to get rid of i
        odd[j++] = *p;
    } else {
        even[k++] = *p;
    }
    p++;
    i++;
}

even[k] = odd[j] = '\0';