I'm trying to get a factorial to be displayed as for example (factorial of 5 is 5*4*3*2*1)
I'm using a method for the factorial, but it doesn't accept the line Console.Write(i + " x "); in my code.
Any help would be great.
here is my code.
//this method asks the user to enter a number and returns the factorial of that number
static double Factorial()
{
string number_str;
double factorial = 1;
Console.WriteLine("Please enter number");
number_str = Console.ReadLine();
int num = Convert.ToInt32(number_str);
// If statement is used so when the user inputs 0, INVALID is outputed
if (num <= 0)
{
Console.WriteLine("You have entered an invalid option");
Console.WriteLine("Please enter a number");
number_str = Console.ReadLine();
num = Convert.ToInt32(number_str);
//Console.Clear();
//topmenu();
//number_str = Console.ReadLine();
}
if (num >= 0)
{
while (num != 0)
{
for (int i = num; i >= 1; i--)
{
factorial = factorial * i;
}
Console.Write(i + " x ");
Console.Clear();
Console.WriteLine("factorial of " + number_str.ToString() + " is " + factorial);
factorial = 1;
Console.WriteLine("(please any key to return to main menu)");
Console.ReadKey();
Console.Clear();
topmenu();
}
}
return factorial;
}
Thank you!
The problem is that your for loop isn't using braces, so the scope is just one line.
Try adding braces appropriately:
for (int i = num; i >= 1; i--)
{
factorial = factorial * i;
Console.Write(i.ToString() + " x ");
}
Console.WriteLine("factorial of " + number_str.ToString() + " is " + factorial);
Without the braces, the i variable only exists on the next statement (factorial = factorial * i;), and no longer exists in scope by the time you call Console.Write.
You will likely also want to remove the call to Console.Clear immediately following this Write, or you will not see it.
here's a solution to consider
public static void Main()
{
Console.WriteLine("Please enter number");
int input;
while (!int.TryParse(Console.ReadLine(), out input) || input <= 0)
{
Console.WriteLine("You have enter an invald option");
Console.WriteLine("Please enter number");
}
Console.Write("Factorial of " + input + " is : ");
int output = 1;
for (int i = input; i > 0; i--)
{
Console.Write((i == input) ? i.ToString() : "*" + i);
output *= i;
}
Console.Write(" = " +output);
Console.ReadLine();
}
int.TryParse() will be beneficial for you, so the program doesn't crash if the user inputs a non-integer
also, you may want something besides an integer. Factorials get very large very fast - anything over 16 will return a wrong result.
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++;
I am a beginner in C# programming and trying to code a method that ask the user to give a start and an end integer number, then sum up all numbers from the start to the end and in case the given start number is greater than the end number, swap the values so that the start number becomes the end number and the end number gets the value of the start number.
This what I have done so far but I'm not getting the right answer when running the app:
private void SumNumbers()
{
int startNumber, endNumber;
Console.WriteLine("\nplease enter a start number: ");
startNumber = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("\nplease enter an end number: ");
endNumber = Convert.ToInt32(Console.ReadLine());
int result = 0;
for (int i=0; i<=startNumber; i=i+1)
{
result = result + i;
Console.WriteLine(i);
}
Console.ReadLine();
Console.WriteLine("The sum of Numbers between " + startNumber + " and " + endNumber + " is: " + result.ToString());
Console.ReadLine();
}
I'm getting this result: The sum of Numbers between 12 and 23 is: 78 when the result actually need to 210.
for (int i=0;i<=startNumber;i=i+1)
You are iterating from 0 to startNumber, when really you want to iterate like startNumber to endNumber.
Try
for (int i = startNumber; i <= endNumber; i = i+1)
Below is the working example.
I also added some logic to handle the checking of the input (whether it is correct or no) so the application doesn't break. This way the user experience is much better.
Here is the live working example: code
private void SumNumbers()
{
int startNumber, endNumber;
Console.WriteLine("\nplease enter a start number: ");
do
{
var input1 = Console.ReadLine();
if (Regex.IsMatch(input1, #"^\d+$"))
{
startNumber = Convert.ToInt32(input1); break;
}
else
{
Console.WriteLine("Input provided is invalid. Please enter a correct number: ");
}
} while (true);
Console.WriteLine("\nplease enter an end number: ");
do
{
var input2 = Console.ReadLine();
if (Regex.IsMatch(input2, #"^\d+$"))
{
endNumber = Convert.ToInt32(input2); break;
}
else
{
Console.WriteLine("Input provided is invalid. Please enter a correct number: ");
}
} while (true);
int min = Math.Min(startNumber, endNumber);
int max = Math.Max(startNumber, endNumber);
int result = 0;
for (int i = min; i <= max; i++)
{
result = result + i;
Console.WriteLine(i);
}
Console.WriteLine("The sum of Numbers between " + min + " and " + max + " is: " + result.ToString());
Console.ReadLine();
}
I mean how to count and sum input numbers until receive "end".
thanks !
And also how to find out input is number or letter in c#?
class Program
{
static void Main(string[] args)
{
int n = 0;
int sum = 0;
string inp;
do
{
Console.Write("Numbers ");
inp = Console.ReadLine();
int num= Convert.ToInt16(inp);
sum = sum + num;
n++;
} while (too == "end");
int average = sum / n;
Console.WriteLine(" " + average);
Console.ReadLine();
}
}
I would suggest you use a normal while loop and also add validation to check to integer input.
For the while loop you want to loop until the input is not equal to "end":
while(inp != "end")
For the validation, you can use int.TryParse method:
int num = 0;
if (int.TryParse(inp, out num)) { }
Here is a modified example of your code:
int n = 0;
int sum = 0;
string inp = null;
while(inp != "end")
{
Console.Write("Numbers ");
inp = Console.ReadLine();
int num = 0;
if (int.TryParse(inp, out num))
{
sum = sum + num;
n++;
}
}
int average = sum / n;
Console.WriteLine(" " + average);
Console.ReadLine();
// A list to hold all of the numbers entered
List<int> numbers = new List<int>();
// Will hold the inputted string
string input;
// This needs to be outside the loop so it's written once
Console.Write("Numbers: " + Environment.NewLine);
// Keep going until we say otherwise
while (true)
{
// Get the input
input = Console.ReadLine();
// Will hold the outcome of parsing the input
int number = -1;
// Check to see if input was a valid number
bool success = int.TryParse(input, out number);
// If it was a valid number then remember it
// If ANY invalid or textual input is detected then stop
if (success)
numbers.Add(number);
else
break;
}
// Write the count and average
Console.WriteLine("Count:" + numbers.Count);
Console.WriteLine("Average:" + numbers.Average());
Console.ReadLine();
Input:
Numbers:
1
2
3
4
5
Output:
Count: 5
Average: 3
The only thing here a little different to what you specified is ANY invalid or textual entry causes it to finish, not just typing the word "end", although that obviously works too.
Basically I've created a times table app. At the end of the app, I've been able to say how many times I got it wrong, and how many times I got it right.
However I want it to say:
You got:
6 x 4 wrong 6 times.
5 x 2 wrong 9 times.
etc...
Rather than you got 20 correct, and 8 wrong.
So I can see the specific multiplications I got wrong. I know where I need to add the code (under the else statement). But not sure how to go about this.
I thought the best solution would be storing all the wrongs as a string in an array, then counting identical strings and outputting a number. But I have no idea how to do this.
Here's my code:
namespace TimesTablesGame
{
class multiplication
{
Random rng = new Random();
int randomNumber;
int randomNumberTables;
int c = 0;
int w = 0;
int numberOfGos = 0;
int minRangeTables;
int maxRangeTables;
int minRange;
int maxRange;
public multiplication()
{
start:
Console.Clear();
Console.WriteLine("\nPlease enter the lowest number range you would like to practice your times tables on: ");
minRangeTables = int.Parse(Console.ReadLine());
Console.WriteLine("\nPlease enter the higest number range you would like to practice your times tables on: ");
maxRangeTables = int.Parse(Console.ReadLine());
Console.WriteLine("\nPlease enter the number of times you would like play: ");
numberOfGos = int.Parse(Console.ReadLine());
Console.WriteLine("\nPlease enter the minimum range you would like to multiply by: ");
minRange = int.Parse(Console.ReadLine());
Console.WriteLine("\nPlease enter the maximum range you would like to multiply by: ");
maxRange = int.Parse(Console.ReadLine());
repeat:
Console.Clear();
for (int i = 1; i <= numberOfGos; i++)
{
randomNumberTables = rng.Next(minRangeTables, maxRangeTables + 1);
randomNumber = rng.Next(minRange, maxRange + 1);
Console.Write("\n\n{0}: {1} x {2} = ", i, randomNumberTables, randomNumber);
if (randomNumberTables * randomNumber == int.Parse(Console.ReadLine()))
{
Console.WriteLine("Correct");
c++;
}
else
{
Console.WriteLine("Wrong it is: " + randomNumberTables * randomNumber);
w++;
}
}
Console.WriteLine("\nYou were correct {0} times, and wrong {1} times.", c, w);
Console.ReadLine();
Console.WriteLine("Would you like to play again? Type y for Yes with new settings, r for repeat using last settings, and any other key to exit.");
char again = Console.ReadKey().KeyChar;
if (again == 'y')
{
c = 0;
w = 0;
goto start;
}
else if (again == 'r')
{
c = 0;
w = 0;
goto repeat;
}
}
}
}
I'd keep track in a Dictionary....
Resisting the urge to re-write the GOTO stuff.....here's a relatively simple way to do it:
Dictionary<string, int> wrongs;
//Console questions...
//Begin looping logic
wrongs = new Dictionary<string, int>();
for (int i = 1; i <= numberOfGos; i++)
{
randomNumberTables = rng.Next(minRangeTables, maxRangeTables + 1);
randomNumber = rng.Next(minRange, maxRange + 1);
string eq = String.Format("{0} x {1} = ", randomNumberTables, randomNumber);
Console.Write("{0}: " + eq, i);
if (randomNumberTables * randomNumber == int.Parse(Console.ReadLine()))
{
Console.WriteLine("Correct");
c++;
}
else
{
Console.WriteLine("Wrong it is: " + randomNumberTables * randomNumber);
if (wrongs.Any(x => x.Key == eq))
{
wrongs[eq]++;
}
else
{
wrongs.Add(eq, 1);
}
w++;
}
}
Console.WriteLine("\nYou were correct {0} times, and wrong {1} times.", c, w);
Console.WriteLine("\n\nYou got:");
foreach (var item in wrongs)
{
Console.WriteLine("{0} wrong {1} times", item.Key, item.Value);
}
//Your logic to repeat/restart
Also....note that this does not count "2 x 4" and "4 x 2" as the same equation....
Also also....You can easily do this without using GOTO....please consider it.
In C# how do i ask user for starting and stopping point within the array?
Below is my code so far:
class Program
{
static void Main(string[] args)
{
double[] num = { 10, 20, 30, 40, 50 };
double n = num.Length;
Console.Write("Elements of, arrary are:" + Environment.NewLine);
for (int i = 0; i < n; i++)
{
Console.WriteLine(num[i]);
}
double sum = 0;
for (int i = 0; i < n; i++)
{
sum = sum + num[i];
}
Console.WriteLine("The sum of elements:" + sum);
Console.ReadKey();
}
}
You'll take the sum of the elements between starting and stopping point, as I guess. Take two inputs from the user and assign them to starting and ending points to the for-loop. Such as:
int startingPoint = Convert.ToInt32(Console.ReadLine());
int endingPoint = Convert.ToInt32(Console.ReadLine());
for(int i = startingPoint; i <= endingPoint; i++)
{
//take sum etc.
}
Don't forget to inform the user about the element values in the array and what input value they are entering at that moment.
Another important thing here is to control the inputs. They should be numeric and between 0-n, starting point should be smaller than ending point.
For numeric control you can write like follows:
if (int.TryParse(n, out startingPoint))
{
// operate here
}
else
{
Console.WriteLine("That's why I don't trust you, enter a numeric value please.");
}
startingPoint should be between 0-n and cannot be n. To control it:
if (startingPoint >= 0 && startingPoint < n)
{
// operate here
}
else
{
Console.WriteLine("Please enter a number between 0 and " + n + ".");
}
After taking startingPoint successfully, you should control if endingPoint. It should be between startingPoint-n. After controlling for being numeric you can write as follows:
if (endingPoint >= startingPoint && endingPoint < n)
{
// operate here
}
else
{
Console.WriteLine("Please enter a number between " + startingPoint + " and " + n + ".");
}
I don't know what can I explain more for this question. Please let me know for further problems.
If you want to prompt the user for the start and end indexes:
Console.WriteLine("Please enter start index");
string startIndexAsString = Console.ReadLine();
int startIndex = int.Parse(startIndexAsString);
Console.WriteLine("Please enter end index");
string endIndexAsString = Console.ReadLine();
int endIndex = int.Parse(endIndexAsString);
var sum = num.Skip(startIndex).Take(endIndex - startIndex + 1).Sum();