A user enters two prime numbers which are then multiplied together, and another calculation of (a-1) * (b-1) is completed (a and b being the prime numbers entered). a function to checks the numbers entered, if the numbers are NOT prime, the user will be asked to re-enter the numbers. However, when I test this, I've noticed that if the user inputs a number which ISN'T prime, and then re-enters a prime number, the calculations are based on the number which ISN'T prime. E.g. if the user enters 2 and 4, since 4 isn't prime they are asked to enter another number, e.g 3, the calculations will be based on the numbers 2 and 4.
How can I correct this so it takes the valid prime number and not the invalid number originally entered?
namespace example
{
class Program
{
class Co_P
{
static void coprime(ref int c, int calculation)
{
if (gcd(c, calculation) == 1)
Console.WriteLine("it's Co-Prime");
else
do
{
Console.WriteLine("it isn't Co-Prime");
Console.WriteLine("Enter a Co-Prime");
c = int.Parse(Console.ReadLine());
coprime(ref c, calculation);
} while (gcd(c, calculation) != 1);
}
static int Prime_a(int a) //check a is prime
{
if (a <= 1) return 0;
for (int i = 2; i <= a / 2; i++)
{
if (a % i == 0)
{
return 0; //not prime
}
}
return 1;
}
static void result(int a) //outputs if a is prime/or not
{
if (Prime_a(a) != 0)
{
Console.WriteLine(a + " is a prime number");
}
else do
{
Console.WriteLine(a + " isn't prime number");
Console.WriteLine();
Console.WriteLine("Please make sure you enter a prime number");
a = int.Parse(Console.ReadLine());
} while (Prime_a(a) == 0);
}
static int Prime_b(int b)
{
if (b <= 1) return 0;
for (int i = 2; i <= b / 2; i++)
{
if (b % i == 0)
{
return 0;
}
}
return 1;
}
static void resultb(int b)
{
int result = Prime_b(b);
if (Prime_b(b) != 0)
{
Console.WriteLine(b + " is a prime number");
}
else do
{
Console.WriteLine(b + " is not a prime number");
Console.WriteLine("Please make sure you enter a prime number");
b = int.Parse(Console.ReadLine());
} while (Prime_b(b) == 0);
}
static void Main(string[] args)
{
int a;
Console.WriteLine("Enter a prime number for a");
a = int.Parse(Console.ReadLine());
Console.WriteLine();
result(a);
Console.WriteLine();
int b;
Console.WriteLine("Enter a prime number for b");
b = int.Parse(Console.ReadLine());
Console.WriteLine();
resultb(b);
Console.WriteLine();
int total = a * b;
Console.WriteLine("The total of the prime numbers is = " + total);
int calculation = (a - 1) * (b - 1); //calculation
Console.WriteLine();
Console.WriteLine("The result = " + calculation);
Console.WriteLine();
}
}
}
You should extend result and resultb function so it returns new prompted valid number
static int result(int a) {
var result = Prime_a(a);
if (result != 0)
...code...
return result
}
Also don't forget to reassign those values
...code...
a = result(a);
...code...
b = resultb(b);
int b;
Console.WriteLine("Enter a prime number for b");
b = int.Parse(Console.ReadLine());
Console.WriteLine();
resultb(b);
Console.WriteLine();
In line resultb(b); you are passing int to method resultb. int is a value type, or in other words, passing int to a method means passing its value to a method, where copy of that value is created. In this case a copy of b is created in method resultb. Every further change on b inside method resultb is made on copy and original stays the same.
In resultb method pass parameter by reference by adding ref keyword. Instead
static void resultb(int b)
{
// code
}
method will look like this
static void resultb(ref int b)
{
// code
}
You will call the method this way
resultb(ref b);
Here's the portion of code.
int b;
Console.WriteLine("Enter a prime number for b");
b = int.Parse(Console.ReadLine());
Console.WriteLine();
resultb(ref b);
Console.WriteLine();
Now every change on passed b inside method resultb will reflect on the original.
You should do the same for method result(int a).
Related
I am currently working on a program that is a loop with a sentinel value that asks the user to enter a number or enter -99 to end the program and it runs perfectly. If I were to change that -99 to just the word "Quit" is there a certain parameter that I would have to put? For example, if I want to use a letter, I know that I could use:
char (undefined parameter) = 'A'
But how would I do this with a word? When I simply try to change the value of -99 to Quit, I receive an error as expected.
using System;
class Program {
public static void Main (string[] args) {
int sum = 0;
int counter = 0;
int max = Int32.MinValue;
int min = Int32.MaxValue;
bool keepGoing = true;
while(keepGoing) {
Console.WriteLine("Please enter a number or enter -99 to stop the program:");
int number = Convert.ToInt32(Console.ReadLine());
if (number == -99){
keepGoing = false;
} else {
counter++;
sum += number;
if (number >= max) {
max = number;
}
if (number <= min) {
min = number;
}
}
}
double average = (double) sum / counter;
Console.WriteLine($"{counter} numbers were entered.");
Console.WriteLine("The average is:" + average);
Console.WriteLine("The sum is:" + sum);
Console.WriteLine("The maximum value is:" + max);
Console.WriteLine("The minimum value is:" + min);
}
}
It's difficult to store "Quit" in an int, so the root of your problem is that you have no separation between pulling the string from the console and converting it to an int:
int number = Convert.ToInt32(Console.ReadLine());
if (number == -99){
keepGoing = false;
} else {
counter++;
If you did have a separation, it becomes possible:
string input = Console.ReadLine();
if (input == "Quit"){
keepGoing = false;
} else {
int number = Convert.ToInt32(input);
counter++;
For my C# programming homework, we had to write a program that allows the user to input an integer and use a loop to print out the factors of that integer.
I got the program to output the integers.
The problem is, for example, when I enter in the integer "24", I want the output to be
1 and 2 and 3 and 4 and 6 and 8 and 12 and 24
but the output that comes out is
1 and 2 and 3 and 4 and 6 and 8 and 12 and 24 and
I don't want the extra "and" at the end of my Factors List
Here is what my code looks like:
using System;
namespace ConsoleApp3
{
class Program
{
static void Main(string[] args)
{
int a, b;
Console.WriteLine("Please enter your integer: ");
a = int.Parse(Console.ReadLine());
for (b = 1; b <= a; b++)
{
if (a % b == 0)
{
Console.Write(b + " ");
}
}
Console.ReadLine();
}
}
}
EDIT: The output has to be formatted as
1 and 2 and 3 and 4 and 6 and 8 and 12 and 24
or else I won't get credit for the assignment
You can enumerate factors, and then Join them with " and "
private static IEnumerable<int> Factors(int value) {
// Simplest, not that efficient
for (int i = 1; i <= value; ++i)
if (value % i == 0)
yield return i;
}
...
Console.Write(string.Join(" and ", Factors(24)));
Or you can add " and " before, not after printing factors (i)
int value = 24;
bool firstTime = true;
// Simplest, not that efficient
for (int i = 1; i <= value; ++i) {
if (value % i == 0) {
// print "and" before printing i
if (!firstTime)
Console.Write(" and ");
firstTime = false;
Console.Write(i);
}
}
How about adding the numbers to a List and printing after the loop:
int a, b;
a = int.Parse(Console.ReadLine());
var result = new List<int>();
for (b = 1; b <= a; b++)
{
if (a % b == 0)
{
result.Add(b);
}
}
Console.Write(string.Join(" and ", result));
static void Main(string[] args)
{
//get input from user
Console.WriteLine("Please enter your integer: ");
int a = int.Parse(Console.ReadLine());
//enumerate factors
var factors = Enumerable.Range(1, a)
.Where(i => a % i == 0).ToArray();
//join for nicely printed output
Console.Write(string.Join(" and ", factors));
Console.ReadLine();
}
I would recommend you to create a string and output that string becouse it allows you to do more things with it, then do something like this:
int a, b;
string x="";
Console.WriteLine("Please enter your integer: ");
a = int.Parse(Console.ReadLine());
for (b = 1; b <= a; b++)
{
if (a % b == 0)
{
x=x + b.toString() +" and";
}
}
if you know that always will be an "and" at the end you can simply do this
string x = x.Substring(0, x.Length - 3);
and then
Console.Write(x);
Console.ReadLine();
What I want to do is have random numbers be generated and take those random numbers and put them through a modulus operator. And I want it to ask the user for the answer they think it is and then they will be told if it is right or wrong. This is what I have.
Random rand = new Random();
int minA;
int maxA;
int minB;
int maxB;
int usersAnswer;
Console.WriteLine("what is the minimum value: ");
Int32.TryParse(Console.WriteLine(), out minA);
Console.WriteLine("what is the minimum value: ");
Int32.TryParse(Console.WriteLine(), out maxA);
Console.WriteLine("what is the minimum value: ");
Int32.TryParse(Console.WriteLine(), out minB);
Console.WriteLine("what is the minimum value: ");
Int32.TryParse(Console.WriteLine(), out maxB);
Console.WriteLine("What is the result of {0} % {1}? ", rand.Next(minA, maxA), rand.Next(minB, maxB));
Int32.TryParse(Console.ReadLine(), out usersAnswer);
answer = //directly implementing the random numbers generated with modulous operator)
if(userAnswer == answer)
{
Console.WriteLine("{0} is correct", answer);
}
else
{
Console.WriteLine("Good try, but no: {the random number} % {the other random number} = {0}", not sure, not sure, answer)
}
So what I want to know is how I can directly implement the random numbers already generated from "Console.WriteLine("What is the result of {0} % {1}? ", rand.Next(minA, maxA), rand.Next(minB, maxB));" into a modulus operator equation and get the answer.
I hope this all made sense
You should store your 2 random numbers as new variables in your class:
int RandomOne;
int RandomTwo;
assign them further down
RandomOne = rand.Next(minA, maxA);
RandomTwo = rand.Next(minA, maxA);
and then refer to them in your messaging. Something like:
Console.WriteLine($"What is the result of {RandomOne} % {RandomTwo}?");
Your code have some promblem:
Remember to fix your instructions text
Somthimes, you use writeline(),but readline() actually
You should handle that something might be going wrong, check comment out
Try it
static void Main(string[] args)
{
Random rand = new Random();
int minA, maxA;
int minB, maxB;
int userAnswer;
Console.WriteLine("what is the minimum A: ");
if (!Int32.TryParse(Console.ReadLine(), out minA)) { return; } //If something going wrong, you should handle it.
Console.WriteLine("what is the maximum A: ");
if (!Int32.TryParse(Console.ReadLine(), out maxA)) { return; }
Console.WriteLine("what is the minimum B: ");
if (!Int32.TryParse(Console.ReadLine(), out minB)) { return; }
Console.WriteLine("what is the maximum B: ");
if (!Int32.TryParse(Console.ReadLine(), out maxB)) { return; }
if (minA > maxA) { exchange(ref minA, ref maxA); } //User might have typo,and this is one way to fix it.
if (minB > maxB) { exchange(ref minB, ref maxB); }
int rndA = rand.Next(minA, maxA),
rndB = rand.Next(minB, maxB); //You should restore the random result, or lost it
int result;
try
{
result = calcMod(rndA, rndB); //Directly implementing the random numbers generated with modulous operator
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
return;
}
Console.WriteLine($"What is the result of {rndA} % {rndB}? ");
Int32.TryParse(Console.ReadLine(), out userAnswer);
if (userAnswer == result)
{
Console.WriteLine("{0} is correct", result);
}
else
{
Console.WriteLine($"Good try, but no: {rndA} % {rndB} = {result}");
}
Console.Write("\nPress Any key to leave.");
Console.ReadKey();
}
//Calculate mod result
static int calcMod(int i1, int i2)
{
try
{
return i1 % i2;
}
catch (Exception e)
{
throw e;
}
}
//Swap number
static void exchange(ref int i1, ref int i2)
{
int tmp;
tmp = i1;
i1 = i2;
i2 = tmp;
}
When I enter the number 6 to calculate its factorial, it returns 30 (which is wrong).
Why is my program producing incorrect output?
using System;
namespace Scenario1_2
{
class Program
{
static void Main(string[] args)
{
int counter, number, fact;
Console.WriteLine("Please enter the number you wish to factorize");
number = int.Parse(Console.ReadLine());
fact = number;
for (counter = number - 1; counter >= 1; counter--)
{
fact = fact * counter;
Console.WriteLine("The number you entered was {0} and it's factorial is {1}", number, fact);
Console.ReadLine();
}
}
}
}
You look new to programming, or least C#, so just for fun, this will blow your mind:
using System;
namespace Scenario1_2
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Please enter the number you wish to factorize");
int number = int.Parse(Console.ReadLine());
Console.WriteLine("The number you entered was {0} and it's factorial is {1}", number, Factorial(number));
Console.ReadKey(true);
}
static int Factorial(int n)
{
if (n >= 2) return n * Factorial(n - 1);
return 1;
}
}
}
No loops anywhere, and the function calls itself.
You can also do it like this:
using System;
namespace Scenario1_2
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Please enter the number you wish to factorize");
int number = int.Parse(Console.ReadLine());
Console.WriteLine("The number you entered was {0} and it's factorial is {1}", number, Factorial(number));
Console.ReadKey(true);
}
static int Factorial(int n)
{
return Enumerable.Range(1, n).Aggregate((i, r) => r * i);
}
}
}
Which is all kinds of messed up :) ...but it does get the significant work down to a single line of code.
Then there's my personal favorite, the infinite enumerable:
using System;
namespace Scenario1_2
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Please enter the number you wish to factorize");
int number = int.Parse(Console.ReadLine());
Console.WriteLine("The number you entered was {0} and it's factorial is {1}", number, Factorials().Skip(number-1).First());
Console.ReadKey(true);
}
static IEnumerable<int> Factorials()
{
int n = 1, f = 1;
while (true) yield return f = f * n++;
}
}
}
The program is paused waiting for some input. You need to move the second Console.ReadLine() out of the loop. And likely the Console.WriteLine() unless you want to see each iteration completing.
You need to move two lines out from the for loop. The modified code look like this.
using System;
namespace Scenario1_2
{
class Program
{
static void Main(string[] args)
{
int counter, number, fact;
Console.WriteLine("Please enter the number you wish to factorize");
number = int.Parse(Console.ReadLine());
fact = number;
for (counter = number - 1; counter >= 1; counter--)
{
fact = fact * counter;
}
Console.WriteLine("The number you entered was {0} and it's factorial is {1}", number, fact);
Console.ReadLine();
}
}
}
There are lots of ways to calculate Factorial. You can also do it by creating a recursive function. Google can help you a lot on these basic things.
Thanks!
int n = 4, fact = n;
for (int i = n; i > 1; i--)
{
fact *= (i - 1);
}
Console.WriteLine(fact);
Console.ReadLine();
why are You printing the message inside the loop.put it outside the loop
Console.WriteLine("The number you entered was {0} and it's factorial is {1}", number, fact);
using System;
namespace factorial
{
class Program
{
static void Main(string[] args)
{
int fact = 1;
Console.Write("Enter a number to find factorial:");
int n = int.Parse(Console.ReadLine());
for (int i = n; i > 0; i--)
{
fact = fact * i;
}
Console.Write("Factorial of" + n +"is :"+fact);
Console.ReadLine();
}
}
}
import java.util.Scanner;
public class Chapter5ProblemTwelve
{
public static void main(String [] args)
{
Scanner keyboard = new Scanner(System.in);
int number;
int factor = 1;
int counter;
System.out.print("Enter a positive integer to display the factorial number: ");
number = keyboard.nextInt();
//If the number entered is less then zero. The program will tell the user to enter a positive number
if (number <= 0)
{
System.out.println("Please enter a postive number and rerun the program again.");
}
else
{
// Math work preformed if user enters a postive number. Example if user enters 4.
// 1*1 = 1, 1*2 = 2,1*3 = 3, 1*4 = 4, The program will multiple all the answers together 1*2*3*4 = 24
for (counter = 1; counter <= number; counter++)
{
factor = factor * counter;
}
//display
System.out.println("The factorial number of " + number + " is: " + factor);
}
}
}
using System;
namespace septtwenty
{
class Program
{
static void Main(string[] args)
{
int i, number, fact;
System.Console.WriteLine("Enter the Number");
number = int.Parse(Console.ReadLine());
fact = number;
for (i = number -1; i>=1; i--)
{
fact = fact * i;
}
System.Console.WriteLine("\nFactorial of Given Number is: "+fact);
Console.ReadLine();
}
}
}
I am new to programming and I think I have confused myself I'm trying to make a loop that asks users for integers when the user inputs a integer greater than 100 then the console displays the amount of integers the user has input and the sum of these integers. I know it's basic but I can't figure where I went wrong.
namespace Wip
{
class Program
{
static void Main(string[] args)
{
string strNum1, strNum2;
int num1, num2;
int i = 0;
int sum =0 ;
Console.WriteLine("Please enter a integer between 1 and 100"); // asks for user input
strNum1 = Console.ReadLine();
num1 = int.Parse(strNum1);
do //repeat asking for user input
{
Console.WriteLine("Please enter another integer between 1 and 100"); // asks for user input
strNum2 = Console.ReadLine();
num2 = int.Parse(strNum2); //input is stored as num2
sum = num2; //store num2 in sum
i++;
if (num2 >= 100) // if num2 int is greater than 100
{
sum = (num1 +num2 +sum); // do calculation
Console.WriteLine("No of integers entered is {0} {1}", i, sum); //output calculation
}
}
while (i < 100);
}
}
}
any help would be appreciated thanks everyone!
You're on the right track... a couple of things:
Do... While is used when you always want to run through the block at least once, so your first 'get' from the user can be inside the block. You can code whatever you want to happen after the condition fails right after the block, instead of checking the same condition inside it.
Make sure if you're simply using Parse that you wrap it in a try...catch, because your user could type in anything (not just numbers). Personally I usually use TryParse instead.
Finally, make sure you're comparing to the correct variable. Checking that i < 100 will keep looping until 100 numbers have been entered; you want to compare the user's input instead.
namespace Wip
{
class Program
{
static void Main(string[] args)
{
string prompt = "Please enter {0} integer between 1 and 100";
string strNum;
int num = 0;
int i = 0;
int sum =0 ;
do //ask once and repeat while 'while' condition is true
{
string pluralPrompt = i > 0 ? "another" : "an";
prompt = string.Format(prompt,pluralPrompt);
Console.WriteLine(prompt); // asks for user input
strNum = Console.ReadLine();
if (!Int32.TryParse(strNum, out num)) //input is stored as num
{
// warn the user, throw an exception, etc.
}
sum += num; //add num to sum
i++;
}
while (num < 100);
Console.WriteLine("No of integers entered is {0} {1}", i, sum); //output calculation
}
}
}
namespace Wip
{
class Program
{
static void Main(string[] args)
{
string strNum;
int num;
int i = 0;
int sum = 0;
do //repeat asking for user input
{
Console.WriteLine("Please enter another integer between 1 and 100"); // asks for user input
strNum = Console.ReadLine();
if (int.TryParse(strNum, out num)) //input is stored as num2
{
if (num < 101)
{
i++;
sum += num;
continue;
}
else
{
Console.WriteLine("No of integers entered is {0} {1}", i, sum); //output calculation
break;
}
}
}
while (i < 100);
}
}