Q. Write your code in the file LuckyNines.java . Use the IO module for all input

Question

Q. Write your code in the file LuckyNines.java. Use the IO module for all inputs and outputs.

Your task is to write a method called

The lower end of the range

The upper end of the range

Then call countLuckyNines(lowerEnd, upperEnd) with the user input values; countLuckyNines(lowerEnd, upperEnd) returns the number of nines that appear in the sequence from lower end to upper end (inclusive).
Hint: Some numbers have more than 1 nine, and not every 9 appears in the ones place.
Hint2: Nested loops are helpful
On error (i.e. upper end is less than lower end) countLuckyNines returns -1.

Example:

Explanation / Answer

// for input
import java.util.Scanner;

public class LuckyNines{
// a static method taking 2 input parameters
public static int countLuckyNines(int lowerEnd,int upperEnd)
{
// returning -1 if lowerbound is greater
if(lowerEnd > upperEnd)
return -1;
  
// Proceeding if valid
int i, help, nines = 0;
// checking every number in between lower and upper bounds
for(i=lowerEnd;i<=upperEnd;i++)
{
// counting the number of 9s in each number
help = i;
while(help>0)
{
if(help%10 == 9) // checking whether a digit is 9
nines++; // increasing nines by 1
help = help/10; // dividing by 10
}
}
// returning the number of nines
return nines;
}

// main method
public static void main(String []args){
  
// for input
Scanner sc = new Scanner(System.in);
  
// taking user input
int upperEnd, lowerEnd;
System.out.print("Enter lower bound: ");
lowerEnd = sc.nextInt();
System.out.print("Enter upper bound: ");
upperEnd = sc.nextInt();
  
// printing and calling the function countLuckyNines
System.out.printf("RESULT: %d ", countLuckyNines(lowerEnd,upperEnd));
}
}

/*
SAMPLE OUTPUT

Enter lower bound: 100
Enter upper bound: 150
RESULT: 5

Enter lower bound: 1
Enter upper bound: 100
RESULT: 20

*/

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