# Check whether the given number is a Duck number or not in Java.

In this project, we are going to check whether the user entered number is a Duck number or not in Java language. We will learn what is a Duck number, what functions and methods we have used.

In this tutorial, we will study whether the given number is a Duck number or not in Java.

Duck number: A Duck number is a positive integer number that contains zeroes in it.

For example, 1024 is considered a Duck number but 0124 is not. Number leading or initiating with zero is not considered as a Duck number.              Even 00124 is not a duck number.

What logic are we using to check on duck numbers?                                                                                                                                     Firstly, we will take input from the user. Then call a static boolean function to check it.

Once we call the static boolean function, we measure the string's length and use a special method - charAt( )

The charAt() is a method that returns the character at a specified number in the string.

Example:

Return the first character of charAt( )-

```public class printstring {
public static void main(String[] args) {
String Str = "Hello World";
char op = Str.charAt(0);
System.out.println(op);
}
}```

```The output of this function: H```

Now, In this code, we have used two while loops:

1) First, While loop to check the initial digits.

2) Second, While loop to check the remaining digits of the given number.

Our second while loop decides whether the given number is a duck number or not. As when "number.charAt(x) == z" will be satisfied in the If-else conditional statement then the boolean statement(true/false) is returned and based on that main driver method if-else is operated.

Note: Here, we have defined number in the string because charAt( ) only works on the string.

```import java.util.Scanner;

// Check whether the given number is duck number or not in Java.

// Main class named Ducknumber.
public class Ducknumber{

// Function to check the given number is duck number or not.

static boolean checkducknumber(String number)
{
int x = 0;
int l;
l = number.length();
int z='0';
while (x < l && number.charAt(x) == z)
//The charAt() is a method which returns the character at a specified number in the string.
{
x++;                 // Ignore the initial zeroes(0's).
}
while (x < l)
{
if (number.charAt(x) == z) // Check the remaining digits in the number.
{
return (true);
}
x++;
}

return(false);
}

// Driver Method of this code.

public static void main(String args[])
{
Scanner scan = new Scanner(System.in);
System.out.println("Enter the number:");
String number = scan.nextLine();
if (checkducknumber(number))
{
System.out.println("The given number is a duck number");
}
else
{
System.out.println("The given number is not a duck number");
}
}
} ```