This is what I am supposed to do:
Write a Java program that will compute the factorial of some numbers n (input from the user, accept only range 1 - 10). For each valid number in input, the output should be the value of n!. Your program should use a loop, to allow the user to input more than one number (count-controlled or sentinel-controlled, your choice)
This is what I have at the moment:
public static void main(String[] args)
{
Scanner console = new Scanner(System.in);
int num, result = 1;
String str;
System.out.print("Do you want to start? (y/n) ");
str = console.next();
System.out.println();
while(str.charAt(0) == 'y')
{
System.out.print("Enter an integer (1 - 10): ");
num = console.nextInt();
if(num < 1 || num > 10)
{
System.out.print("NUMBER OUT OF RANGE!");
num = console.nextInt();
}
else
{
int i = 2;
while(i <= num)
{
result = result * i;
i++;
}
System.out.println(num + "! = " + result);
System.out.println();
System.out.print("Do you want to continue? ");
str = console.next();
}
System.out.println();
}
}
But this is my result:
Do you want to start? (y/n) y
Enter an integer (1 - 10): 1
1! = 1
Do you want to continue? y
Enter an integer (1 - 10): 2
2! = 2
Do you want to continue? y
Enter an integer (1 - 10): 3
3! = 12
Do you want to continue? y
Enter an integer (1 - 10): 4
4! = 288
I can't get the output to display the right results, that is the only problem I am having with my program. Also, it shows the correct result the first time you are asked to enter an integer, but after that, everything goes wrong
Try this code:
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner console = new Scanner(System.in);
String str;
System.out.print("Do you want to start? (y/n) ");
str = console.next();
System.out.println();
int num, result;
while (str.charAt(0) == 'y') {
System.out.print("Enter an integer (1 - 10): ");
num = console.nextInt();
while (num < 1 || num > 10) {
System.out.println("NUMBER OUT OF RANGE!");
System.out.print("Enter an integer (1 - 10): ");
num = console.nextInt();
}
int i = 2;
result = 1;
while (i <= num) {
result = result * i;
i++;
}
System.out.println(num + "! = " + result);
System.out.println();
System.out.print("Do you want to continue? ");
str = console.next();
System.out.println();
}
}
}
You need to set result = 1 inside your outer while loop, not before it. What's happening here is that the numbers you're multiplying are getting multiplied by the result from the previous iteration of the outer while loop.
You are not resetting the result when you iterate for a new value.
Just reset the result to 1 before you start calculating factorial
e.g. -
while(str.charAt(0) == 'y')
{
result =1;
I think you're having a logical error with your if statement. Having a range of 1-10, your if statement should look something like this:
if(userInput>0 && userInput<=10);
Also, as what David Wallace has stated, you need to re-initialize your variable i back to 1 after your inner "factorial while loop" finishes. In this way, your variable i would always have the starting value of 1 whenever it enters your inner factorial while loop.
I would begin by creating a lookup table for the valid range of factorials. That might be done iteratively, create a fact array and fill it. Something like,
int[] fact = new int[10];
int i;
fact[0] = i = 1;
while (i < fact.length) {
fact[i] = (i + 1) * fact[i - 1];
i++;
}
Then you can use an infinite loop with your Scanner (breaking on non-integer input) and the fact lookup table like,
Scanner scan = new Scanner(System.in);
while (true) {
System.out.println("Enter a number 1-10 for the factorial (or a "
+ "non-number to quit): ");
if (!scan.hasNextInt()) {
break;
}
i = scan.nextInt();
if (i < 1 || i > 10) {
System.out.println("NUMBER OUT OF RANGE!");
continue;
}
System.out.printf("%d! = %d%n", i, fact[i - 1]);
}
Related
I'm fairly new to Java and the problem I am having is that this code compiles, but does not run after the hexadecimal conversion; it instead just ends after the method hexCharToDecimal. I can't reuse method main and I'm not sure how to call the method intreverse and actually have it run. Is there a way to get back into main or do I have to call intreverse somewhere?
import java.util.Scanner;
public class Homework4 {
public static void main(String[]args) {
// Sum and average of a set of intergers entered by the user
// First we will declare some variables
int userInput = 1;
int positives = 0;
int negatives = 0;
int sum = 0;
int numCount = 0;
Scanner input = new Scanner(System.in);
// Will start a while loop that will stop when user enters 20 integers
while ((numCount <= 20)) {
System.out.println("Please enter a nonzero integer or enter 0 to finish ");
userInput = input.nextInt();
if (userInput == 0) {
break;
} else if (userInput > 0) {
positives += 1;
numCount += 1;
sum = sum + userInput;
} else if (userInput < 0) {
negatives += 1;
numCount += 1;
sum = sum + userInput;
} else
System.out.println("Error, please enter an integer");
continue;
}
double average = (sum / numCount);
System.out.println("The sum of the entered integers is " + sum);
System.out.println("The average of the enetered integers is " + average);
System.out.println("There are " + positives + " positive integers and " + negatives + " negative integers");
// Convert Hexadecimal number to decimal
// Ask the user to input a string of 5 digits or less in hex
System.out.println("Please enter a hexadecimal number of up to 5 characters");
String hex = input.next();
if (hex.length() <= 5) {
System.out.println(hex + " in decimal value is equal to " + hexToDecimal(hex.toUpperCase()));
} else {
System.out.println("Error: please enter a hex number of 5 digits or less");
}
}
// Now we will create the method to convert to decimal
public static int hexToDecimal(String hex) {
int decimal = 0;
for (int i = 0; i < hex.length(); i++) {
char hexcharacter = hex.charAt(i);
decimal = decimal * 16 + hexCharToDecimal(hexcharacter);
}
return decimal;
}
public static int hexCharToDecimal(char ch) {
if (ch >= 'A' && ch <= 'F') // check to see if there is any letters in the string
return 10 + ch - 'A';
else
return ch - '0';
}
// Print entered integer in reverse
public static void intreverse(String[]args) {
// Ask user for an integer to be reversed
Scanner input = new Scanner(System.in);
System.out.println("Please enter an integer to be reversed");
int number = input.nextInt();
reverse(number); // Method to be called
}
// Will now state our method
public static void reverse(int number) {
// use a while loop to get each digit
while (number > 0) {
System.out.print(number % 10);
number = number / 10;
}
}
}
if (hex.length() <= 5) {
System.out.println(hex + " in decimal value is equal to " + hexToDecimal(hex.toUpperCase()));
} else {
System.out.println("Error: please enter a hex number of 5 digits or less");
}
Will always run once because it is not enclosed in any sort of loop. If you want it to run again when the second case is called then enclose it in a while(true) loop and have a break statement in the first case where you want it to stop execution.
My code is supposed to ask for a name, ask for a number between one and ten, print the numbers from 1 to the number the user entered except every third number should
be the user's name that was entered at the beginning of the program, print the even numbers, continually ask the user for numbers until the user enters the sentinel, and then print the total of the numbers entered. (I know, that's a lot.) My code is running fine, the only problem I am having is with the last part. Even when the user enters the sentinel, which in this case is -1, the program still asks for another entry.
Did I do something wrong when declaring the variable or can someone explain how to fix my problem? Here is my code.
import java.util.Scanner;
/**
*
* #author Home
*/
public class NewClass1 {
public static void main(String[] args) {
int number;
Scanner scan = new Scanner( System.in);
System.out.print( "Enter your name: ");
String name = scan.nextLine();
System.out.print( "Please enter a number between 1 and 10: ");
number = scan.nextInt();
//asks for a number between one and ten until I get number within that range,
while (number < 1 || number > 10) {
System.out.print( "No, between 1 and 10: ");
number = scan.nextInt();
}
for (int i = 1; i <= number; i++) {
if (i % 3 == 0) {
System.out.print(name + " ");
} else {
System.out.print(i + " ");
}
}
System.out.println();
for(int i =2; i<=number; i+=2)
System.out.print(i + " ");
System.out.print("are the even numbers.");
final int SENTINEL = -1;
int inputNumber;
int total = 0;
System.out.println(" Enter a number or -1 to finish. " );
inputNumber = scan.nextInt();
while ( inputNumber != SENTINEL )
{
total += number;
System.out.print("Enter the next number or '-1' to finish. ");
number = scan.nextInt();
}
System.out.println( "The total is " + total);
}
}
Solution:
You get input from user and saving that input in varible called number but you are checking your while against inputNumber.
while ( inputNumber != SENTINEL )
{
total += number;
System.out.print("Enter the next number or '-1' to finish. ");
inputNumber = scan.nextInt(); <<< not number should be inputNumber
}
public class NewClass1 {
public static void main(String[] args) {
int number;
Scanner scan = new Scanner(System.in);
System.out.print("Enter your name: ");
String name = scan.nextLine();
System.out.print("Please enter a number between 1 and 10: ");
number = scan.nextInt();
//asks for a number between one and ten until I get number within that range,
while (number < 1 || number > 10) {
System.out.print("No, between 1 and 10: ");
number = scan.nextInt();
}
for (int i = 1; i <= number; i++) {
if (i % 3 == 0) {
System.out.print(name + " ");
} else {
System.out.print(i + " ");
}
}
System.out.println();
for (int i = 2; i <= number; i += 2) {
System.out.print(i + " ");
}
System.out.print("are the even numbers.");
final int SENTINEL = -1;
int inputNumber;
int total = 0;
do {
System.out.println(" Enter a number or -1 to finish. ");
inputNumber = scan.nextInt();
if(inputNumber!= SENTINEL){
total+=inputNumber;
}
} while (inputNumber != SENTINEL);
System.out.println("The total is " + total);
}
}
I have a problem with my program.
Program is a HILO game which requires the user to guess a number between a range of a generated number.
The problem is that once i press 0 on my keyboard, it reveals the random number, and essentially must end the loop and ask whether the user wants to continue or end the program. Instead, it continues the loop, and whenever I press a letter on the keyboard it shows me an Exception error which describes and input Miss Match. Can some one guide me on how to fix it?, maybe I wrote the program wrong, I tried multiple ways, it still doesn't work as it supposed to work.
Thank you.
import java.util.Scanner;
import java.util.Random;
import java.lang.Math;
public class HILOGAME
{
public static void firstGame()
{
final int range = 50;
int answer = 0;
int guesses;
int number;
int guessNum = 0;
String choice = "";
boolean Loop = false;
Scanner input = new Scanner(System.in);
Random r = new Random();
answer = r.nextInt(range) + 1;
System.out.println("IF YOU WISH TO GIVE UP, PRESS 0 ON THE KEYBOARD");
while (!Loop)
{
for (int exit = 0; exit < 10; exit++)
{
System.out.print("Guess a number between 1 and " + range + " : ");
number = input.nextInt();
guessNum = guessNum++;
guessNum += 1;
if (number == answer)
{
System.out.println(" Your guess was correct ");
System.out.println();
System.out.println("The number was: " + answer);
System.out.println("You guess the number with: " + guessNum + " guesses ");
System.out.println();
System.out.println("Enter x to continue to play or y to endgame");
choice = input.nextLine();
if (!choice.equalsIgnoreCase("x"))
{
Loop = true;
answer = r.nextInt(range) + 1;
System.out.print("A new number");
break;
}
else if (choice.equalsIgnoreCase("y"))
{
Loop = false;
System.out.print("END OF GAME");
exit = 11;
}
}
if (number > answer)
{
System.out.println("TOO HIGH");
}
if (number < answer)
{
System.out.println("TOO LOW");
}
if (number == 0)
{
System.out.println("YOU GAVE UP. THE NUMBER WAS " + answer);
System.out.println("Enter x to continue to play or y to endgame");
}
}
}
}
}
EDIT 1:
This code is working perfectly for me i have tried running it:
final int range = 50;
int answer = 0;
int guesses;
int number;
int guessNum = 0;
String choice = "";
boolean Loop = false;
Scanner input = new Scanner(System.in);
Random r = new Random();
answer = r.nextInt(range) + 1;
System.out.println("IF YOU WISH TO GIVE UP, PRESS 0 ON THE KEYBOARD");
while (!Loop)
{
int exit;
for (exit = 0; exit < 10; exit++)
{
System.out.print("Guess a number between 1 and " + range + " : ");
number = input.nextInt();
guessNum = guessNum++;
guessNum += 1;
if (number == answer)
{
System.out.println(" Your guess was correct ");
System.out.println();
System.out.println("The number was: " + answer);
System.out.println("You guess the number with: " + guessNum + " guesses ");
System.out.println();
System.out.println("Enter x to continue to play or y to endgame");
choice = input.next();
// HERE YOU ARE DOING THE WRONG THING
// What is the meaning of "not(!)" here ? !choice.equalsIgnoreCase("x")
// Remove "NOT(!)" from here your program will work as expected
if (choice.equalsIgnoreCase("x"))
{
//here you should assign loop to false if they continue
Loop = false;
answer = r.nextInt(range) + 1;
System.out.print("A new number");
break;
}
else if (choice.equalsIgnoreCase("y"))
{
//better to insert break here as well
//here you should assign loop to true if they wanna exit.
Loop = true;
System.out.print("END OF GAME");
exit = 11;
break;
}
}
else if (number > answer)
{
System.out.println("TOO HIGH");
}
else if (number < answer)
{
System.out.println("TOO LOW");
}
if (number == 0)
{
System.out.println("YOU GAVE UP. THE NUMBER WAS " + answer);
System.out.println("Enter x to continue to play or y to endgame");
// MADE CHANGES HERE
choice = input.next();
if (choice.equalsIgnoreCase("x"))
{
//here you should assign loop to false if they continue
Loop = false;
answer = r.nextInt(range) + 1;
System.out.print("A new number");
break;
}
else if (choice.equalsIgnoreCase("y"))
{
//better to insert break here as well
//here you should assign loop to true if they wanna exit.
Loop = true;
System.out.print("END OF GAME");
exit = 11;
break;
}
}
}
}
Please do copy-paste the code. Because it is working perfectly without any Exception..!!
My sample outputs:
SAMPLE 1:
Guess a number between 1 and 50 : 1
TOO LOW
Guess a number between 1 and 50 : 0
TOO LOW
YOU GAVE UP. THE NUMBER WAS 27
Enter x to continue to play or y to endgame
y
END OF GAME
SAMPLE 2:
Guess a number between 1 and 50 : 20
TOO HIGH
Guess a number between 1 and 50 : 19
TOO HIGH
Guess a number between 1 and 50 : 15
Your guess was correct
The number was: 15
You guess the number with: 3 guesses
Enter x to continue to play or y to endgame
x
A new numberGuess a number between 1 and 50 : 20
TOO LOW
Guess a number between 1 and 50 : 0
TOO LOW
YOU GAVE UP. THE NUMBER WAS 42
Enter x to continue to play or y to endgame
y
END OF GAME
Do let me know if there is any problem.
Well, if you wish to end a loop, you could use the break; command. It jumps out of a while or for loop. So you could use this if the number is 0:
if (number == 0)
{
System.out.println("YOU GAVE UP. THE NUMBER WAS " + answer);
System.out.println("Enter 'x' to continue to play or y to endgame");
choice = input.nextLine();
if(choice == "y")
{
break;
}
and add:
if(choice == "y") {break;} to the very end of the while(!Loop) loop.
And with the time when the answer is correct, you set Loop to false, which means !Loop would evaluate to true. You should change Loop = false to Loop = true when they decide to continue the game.
a small modification
public class HILOGAME {
public static void firstGame() {
final int range = 50;
int answer;
int number;
int guessNum = 0;
String choice = "";
Scanner input = new Scanner(System.in);
Random r = new Random();
answer = r.nextInt(range) + 1;
System.out.print("Guess a number between 1 and " + range + " : ");
number = input.nextInt();
if (number == answer) {
System.out.println(" Your guess was correct ");
System.out.println();
System.out.println("The number was: " + answer);
System.out.println("You guess the number with: " + guessNum + " guesses ");
System.out.println();
} else {
System.out.println("you entered a wrong value");
System.out.println("do you really want to try again? press y to continue or other alphabet to exit");
choice = input.next();
playAgain(choice);
}
}
public static void playAgain(String choice) {
if (choice.equalsIgnoreCase("Y")) {
firstGame();
} else {
System.out.println("you chose to quit");
System.exit(0);
}
}
The idea is to create an average for money made in a week by day and my average must be calculated in a method that is called in the main method. That is the easy part, but the part I'm stuck on is if a number less than zero is entered it should give me an error message and re-prompt the user for a better value. I'm not looking for a handout here just for someone to tell me what I've been doing wrong if it is simple and easy or a pointer in the right direction.
import java.util.*;
public class weeklyAveragesClient2
{
public static void main(String [] args)//output averages in format
{
averageCash();
}
public static double averageCash()//use array and loop to calculate weekly average
{
double [] cashMoney;
cashMoney = new double[7];
Scanner scan = new Scanner(System.in);
int j = 0;
String s = "ERROR";
while (j < 7)
{
double num = cashMoney[j];
if (num == 0)
{
System.out.println("Error please enter a number > 0");
num = j;
cashMoney[j] = scan.nextDouble();
}
else if(num > 0)
{
System.out.print("Please enter an amount for day " + (j+1) +": ");
cashMoney[j] = scan.nextDouble();
j++;
}
else
{
System.out.println("Error: negative number please enter a number > 0");
}
}
System.out.println("Calculating...");
double sum = 0;
for (int i = 0; i < cashMoney.length; i++)
{
sum = sum + cashMoney[i];
}
double average = sum / (double)cashMoney.length;
System.out.println("Average: " + average);
return average;
}//end averageCash
}//end class
I've added some comments that will hopefully provide food for thought.
// This will *always* be zero at first because you haven't called scan.nextDouble() yet
// and zero is the default value. So when you run the program, it will output "Error
// please enter a number > 0" before doing anything else
if (num == 0) {
System.out.println("Error please enter a number > 0");
num = j;
cashMoney[j] = scan.nextDouble();
} else if (num > 0) {
System.out.print("Please enter an amount for day " + (j + 1) + ": ");
cashMoney[j] = scan.nextDouble();
j++;
} else {
// If we get into this state, the user will never be invited to enter
// another number, since the last entered number was negative, so
// num == 0 is false, and
// num > 0 is false, so
// we'll end up back here. In fact, you'll enter an infinite loop and
// this message will be printed over and over again.
System.out.println("Error: negative number please enter a number > 0");
// cashMoney[j] = scan.nextDouble(); // <-- try prompting the user again
}
Please also consider indenting your code correctly. It will greatly increase readability. If you're using an IDE like Eclipse, you can select Source > Format.
Hi all thanks for taking the time, I am continuosly getting an infinate loop when i am inserting the variable m could anyone please take a look thanks.
public static void main program7_2(String args [])
{
Scanner sc = new Scanner (System.in);
System.out.println("Please enter the first number: ");
int n = sc.nextInt();
while((n%2)== 0)
{
System.out.println("The number you entered is incorrect please enter an odd number:");
n = sc.nextInt();
}
System.out.println("Please enter the second number: ");
int m = sc.nextInt();
while((m%2)== 0)
{
System.out.println("The number you entered is incorrect please enter an odd number:");
m = sc.nextInt();
}
int sum =0;
for (int i = n; n<=m; i++)
{
if ((i%2) != 0)
sum = sum + i;
}
System.out.println("Sum of the numbers between "+n+ " and " +m+": " + sum);
}
The problem of the program is to enter 2 odd numbers and get the sum of the odd numbers in between
Thanks and regards
Instead of n<=m in your for loop use i<=m since you are using i as your counter and not n
This is the error :
for (int i = n; n<=m; i++) /* terminating condition "n<=m" is never met here */
{
if ((i%2) != 0)
sum = sum + i;
}
Why : this loop increments i but terminating condition is n<=m which is never met....so either do i<n Or i<m which ever suits you for terminating the condition!!
if u want to get the sum of nubers between those two use
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
System.out.println("Please enter the first number: ");
int n = sc.nextInt();
while ((n % 2) == 0) {
System.out.println("The number you entered is incorrect please enter an odd number:");
n = sc.nextInt();
}
System.out.println("Please enter the second number: ");
int m = sc.nextInt();
while ((m % 2) == 0) {
System.out.println("The number you entered is incorrect please enter an odd number:");
m = sc.nextInt();
}
int sum= 0;
for (int i = n; i <= m; i++) {
sum = sum + i;
}
System.out.println("Sum of the numbers between " + n + " and " + m + ": " + sum);
}
}