Develop Reference

How do I detect an infinite loop occuring in my code?

So my code is to check if a given number is a 'happy number'. It squares each digit of the number, adds them and continues to do so until either the result of the addition is 1 (which means it is a happy number) or until it results in a 4 (which means it is not a happy number).
What's happening is that there are many numbers which cause an infinite loop (therefore meaning they are not a happy number) and I'm wondering how I would construct my code so that it will detect when there's an infinite loop occuring? I have some ideas but all flawed.
My code is as follows:
using System;
namespace Happy_numbers_problem
{
class Program
{
static int HappyNumbers(string Number)
{
string Output = Number;
while ((Convert.ToInt32(Output) != 1) && (Convert.ToInt32(Output) != 4))
{
string Result2 = "0";
for (int Index = 0; Index < Output.Length; Index++)
{
string Character = Output.Substring(Index, 1);
int Calc = Convert.ToInt32(Character);
int Result = Calc * Calc;
//Adding Result2 and Result, then turning it into a string.
Result2 = Convert.ToString(Convert.ToInt32(Result2) + Result);
if (Index == (Output.Length) - 1)
{
Output = Result2;
}
}
}
return Convert.ToInt32(Output);
}
static void Main(string[] args)
{
Console.WriteLine("Please enter a number");
string Number = Console.ReadLine();
int Output = HappyNumbers(Number);
if (Output == 1)
{
Console.WriteLine(Number + " is a happy number");
}
else if (Output == 4)
{
Console.WriteLine(Number + " is not a happy number");
}
else
{
Console.WriteLine(Number + " is not a happy number");
}
}
}
}

The problem resides in your while condition. If your output needs to be 1 or 4 to break out of the loop and deliver the output to latter be analysed, you have to use the operator or || instead of the operator and &&.

Calculating average of all user input numbers using while loops in C#

I'm trying to work through a problem presented in one of my classes. The prompt is telling us to get the user to enter any numbers (can be positive, negative, or 0), while ignoring non-numeric inputs. Then we need to compute and display the average of all the numbers entered by the user. If the user doesn't give any numbers, I need to output "you didn't enter any numbers".
My main issue is that I'm not able to store and add the numbers given by the user properly. I'm fairly certain that everything before and after the while statement is sound. So, I know the issue must lie within while (enter!="Yes"||enter!="yes"||enter!="Y"||enter!="y"), but I'm not exactly sure what the issue is. Since I have variables for my average, the sum of the user given numbers, and a counter to keep track of loop iterations, I'm pretty sure my troubles are coming from my code not being in the correct order.
Console.WriteLine("Please enter any numbers, then type Yes to continue.");
string enter = Console.ReadLine();
string msg = "";
decimal average;
int counter = 0;
decimal sum = 0;
bool res = decimal.TryParse(enter, out average);
while (enter!="Yes"||enter!="yes"||enter!="Y"||enter!="y")
{
sum = decimal.Parse(enter);
Console.WriteLine("Please enter any numbers, then type Yes to continue");
enter = Console.ReadLine();
sum += counter;
counter++;
}
average = sum / counter;
msg = (res) ? $"The sum of your numbers is {average}" : "You didn't enter any numbers";
Console.WriteLine(msg);

try this one
static void Main()
{
int counter = 0;
decimal sum = 0;
bool exit=false;
do
{
Console.WriteLine("Please enter any number or type \"done\" to exit");
var enter = Console.ReadLine();
if (enter.Trim().ToLower() != "done")
{
var ok = decimal.TryParse(enter, out var num);
if(!ok) continue;
sum += num;
counter++;
} else exit=true;
} while (!exit);
var average = counter > 0 ? sum / counter:0;
var msg = average>0? $"The average of your numbers is {average}" : "You didn't enter any numbers";
Console.WriteLine(msg);
}

Here's an alternative for you to play with. Just to give you some more ideas.
string enter = "";
string[] stop = new [] { "yes", "y" };
List<int> numbers = new List<int>();
while (!stop.Contains(enter.ToLowerInvariant()))
{
Console.WriteLine("Please enter any numbers, then type Yes to continue.");
enter = Console.ReadLine();
if (int.TryParse(enter, out int number))
{
numbers.Add(number);
}
}
if (numbers.Any())
{
Console.WriteLine($"The average of your numbers is {numbers.Average()}");
}
else
{
Console.WriteLine("You didn't enter any numbers");
}

Try this......
string enter = "";
string msg = "";
decimal average;
int counter = 0;
decimal sum = 0;
decimal input;
while (enter!="Yes"&&enter!="yes"&&enter!="Y"&&enter!="y")
{
Console.WriteLine("Please enter any numbers, then type Yes to continue");
enter = Console.ReadLine();
bool res = decimal.TryParse(enter, out input);
if (res) {
sum += input;
counter++;
}
}
if (counter != 0)
{
average = sum / counter;
msg = $"The average of your numbers is {average}";
}
else {
msg = "You didn't enter any numbers";
}
Console.WriteLine(msg);
System.Threading.Thread.Sleep(5000);

Stop program from crashing when pressing Enter

So, today I decided to start learning C# from scratch. I've managed to make a little math problems program. The thing is, whenever the user just presses enter without entering a value (or anything which isn't a number), the program crashes. I've read something about TryParse but I just can't get it.
Here's my code (part of it):
{
Random numberGenerator = new Random();
int num01 = numberGenerator.Next(1, 20);
int num02 = numberGenerator.Next(1, 20);
Console.WriteLine("Welcome, user.");
Console.ReadKey();
Fail2:
Console.WriteLine("¿What's " + num01 + "x" + num02 + "?");
int res1 = Convert.ToInt32(Console.ReadLine());
if (res1 == num01*num02)
{
Console.WriteLine("Your answer is correct");
Console.ReadKey();
}
else
{
goto Fail;
}
Thanks in advance!

Hello & welcome to StackOverflow! I have a couple of suggestions:
Avoid using goto
Replace all your Convert.X with X.TryParse whenever it's the user who gives you the value, since you don't know what it could be
Random numberGenerator = new Random();
int num01 = numberGenerator.Next(1, 20);
int num02 = numberGenerator.Next(1, 20);
Console.WriteLine("Welcome, user.");
Console.ReadKey();
// Always use a loop instead of goto statements!
while (true)
{
Console.WriteLine("¿What's " + num01 + "x" + num02 + "?");
// Old line: int res1 = Convert.ToInt32(Console.ReadLine());
// Problem: this assumes that Console.ReadLine() returns a valid number, e.g. "3"
// but as you said, the user can trick you and put something else
if (!int.TryParse(Console.ReadLine(), out int res1))
continue; // This will rerun the loop from the top, so the user will need to re-write a response
if (res1 == num01*num02)
{
Console.WriteLine("Your answer is correct");
Console.ReadKey();
}
else
{
break; // stop the outer loop on top
}
}

Use int.TryParse like this...
int res1 = 0;
if (!int.TryParse(Console.ReadLine(), out res1))
{
//failed;
}
if (res1 == num01*num02)
...
https://learn.microsoft.com/en-us/dotnet/api/system.int32.tryparse?view=netcore-3.1

Cannot create different random numbers in loop

I am new to C# and am having difficulty understanding where I am going wrong in this random number guessing game I have created. I have tried to add a random.next command in the do while loop on line 30, when I run the program it says my guess is either too high or too low, I do not understand what is going wrong. Here is the unfinished code:
static void Main(string[] args)
{
Random random = new Random();
int numberToGuess = random.Next(100) + 1;
int userGuess = 0;
string name;
Console.WriteLine("What is your name?");
name = Convert.ToString(Console.ReadLine());
Console.WriteLine("In this game you need to guess which number the computer has picked in the range of 1 to 100."
+ Environment.NewLine + "If the number you enter is too high or too low the program will display this, " +
Environment.NewLine + "try to make the least amount of guesses as possible!" + Environment.NewLine
+ "==========================================================================================================");
do
{
do
{
Console.Write("Enter your guess: ");
userGuess = Convert.ToInt32(Console.ReadLine());
if (userGuess > numberToGuess)
{
Console.WriteLine(userGuess + " is too high!");
}
else if (userGuess < numberToGuess)
{
Console.WriteLine(userGuess + " is too low!");
}
else
{
Console.WriteLine(userGuess + " SPOT ON! Congratulations.");
}
numberToGuess = random.Next(100) + 1;
} while (userGuess != numberToGuess);
Console.WriteLine("Do you want to continue?");
} while (Console.ReadLine().ToUpper() == "YES");
}
If I remove numberToGuess = random.Next(100) + 1; the code works fine but repeats the same random number.
Please Help.

Debug your application replacing
Console.Write("Enter your guess: ");
With
Console.Write("Enter your guess (" + numberToGuess + "): ");
You will see that the numberToGuess is changing every time... you should comment that line and use only the fist random number generated.

Your number of guess range is very high 1 to 100 and after every time you are generating random number again. Just reduce you size of random generator number for example
int numberToGuess = random.Next(5) + 1;
First check its working good or not then think about expanding it.

This method will return a truly random number.
Public Shared Function RandomInteger(min As Integer, max As Integer) As Integer
Dim Rand As New System.Security.Cryptography.RNGCryptoServiceProvider
Dim scale As UInteger = UInteger.MaxValue
While scale = UInteger.MaxValue
' Get four random bytes.
Dim four_bytes As Byte() = New Byte(3) {}
Rand.GetBytes(four_bytes)
' Convert that into an uint.
scale = BitConverter.ToUInt32(four_bytes, 0)
End While
' Add min to the scaled difference between max and min.
Return CInt(min + (max - min) * (scale / CDbl(UInteger.MaxValue)))
End Function

Guessing Game Number Issue

Before I get down-voted for the extensive code, I feel it's necessary for a solution to present itself.
I've made alterations to the program's code from the help previously presented, but I still seem to be falling into the problem that the random number number is either not being properly compared (I've had examples where number is '5' and the user's guess is '5', but I'm still getting a comment that "You're quite far off! Try again." meaning it's falling into else if (userinputcalc > 4 | userinputcalc < 10)...
So, at this stage the issue seems to lie within the comparison of number and the userinput, leading to confusing output messages.
I'm probably missing something obvious here, despite being sure it's around the loop of comparing number and userinput but I've been looking at this code and seeing nothing.
Any help is greatly appreciated, as always.
public void GuessingGame()
{
string username; // Will be the user's chosen name for program interaction
int guessesleft = 0;// Stands for the number of guesses left (out of 3)
int spaceaway = 0; // Space from the guess and the random number, if not correct guess
int roundcount = 1; //Started at 1 for the sake of the user interface - aesthetics
int number = 0; // Current value of the random number
int userinput = 0; //User input is the guess the user makes during the guessing game
int userinputcalc = 0;// calculation of guess and random number, when added to spaceaway calculation
int answersright = 0; // Number of times the user guessed the number correctly
Random rndm = new Random(); // Initialises a new class of random, which'll be used to simulate the random number
Console.WriteLine("Welcome to Guessing Game!");
Console.WriteLine("");
Console.WriteLine("Please press any button to continue.");
Console.ReadLine();
Console.WriteLine("What's your name?");
username = (Console.ReadLine());
//If you're wondering at all, the "You must guess what it is inthree tries." is intentional, since it was showing double-spaced in the command prompt
Console.WriteLine("Well, " + username + ", I am thinking of a number from 1 to 10. You must guess what it is inthree tries.");
Console.WriteLine("");
{
do
{
Console.WriteLine("Round" + roundcount); //Displays the which round (out of 10) to the user
guessesleft = 3; //The remaining guesses left for the user
do
{
number = rndm.Next(10) + 1; // int number is set to a random number between 1 and 10
Console.WriteLine("Please enter a guess:");
userinput = int.Parse(Console.ReadLine());
guessesleft = guessesleft - 1;
if (userinput == number)
{
//Below, once you've guessed right, you will have this message displayed in the console
Console.WriteLine("You guessed " + number + " *RIGHT*!");
answersright = answersright + 1;
guessesleft = 0;// No point need to guess further on something you've guessed correctly - saves correct answer value exploit
}
else if (userinput < 1 || userinput > 10) // If user's guess is less than 1 or more than 10, then out of range. Counts as a guess.
{
Console.WriteLine("You guessed " + userinput + "! and it was incorrect!");
Console.WriteLine("This is outside of the range of numbers between 1-10 ");
}
else if (userinput != number) // while the user's guess does not equal the number
{
{
// userinputcalc = Math.Abs(number - userinput);
//Left out as I was getting abnormal run-time outputs and the math showed up wrong.
//(Example: RND No. = 5 Userinput = 5 Output: "Incorrect" "Hot")
spaceaway = (number - userinput); // Works out how far from the random no. the user's guess is.
// If user guesses 6 and random no. is 5, answer will be -1 this makes the value +ve and allows output to be shown without error
if (spaceaway < 0)
{
spaceaway = (spaceaway * -1);
userinputcalc = spaceaway;
}
else if (spaceaway > 0)
{
userinputcalc = spaceaway;
}
}
{
if (userinputcalc < 2)
{
Console.WriteLine("You guessed " + userinput + "! and it was wrong!");
Console.WriteLine("Hot");
}
else if
(userinputcalc < 3)
{
Console.WriteLine("You guessed " + userinput + "! and it was wrong!");
Console.WriteLine("Warm");
}
else if
(userinputcalc < 4)
{
Console.WriteLine("You guessed " + userinput + "! and it was wrong!");
Console.WriteLine("Cold");
}
else if (userinputcalc > 4 | userinputcalc < 10)
{
Console.WriteLine("You guessed " + userinput + "! and it was wrong!");
Console.WriteLine("You're quite far off! Try again.");
}
}
}
} while (guessesleft > 0);
Console.WriteLine("");
Console.WriteLine("The number was, "+number+"!");
Console.WriteLine("");
roundcount = roundcount + 1;
} while (roundcount < 11);
Console.WriteLine("Well, " + username + ". " + "You guessed correctly, " + answersright + " times!");
}
}
}
}

OK I think theres quite a few issues here (some are off topic but definitely worth mentioning)..
I wouldn't advise using while loops to check for specific inputs
For example:
Instead of roundCount != 11 use roundCount < 11
Then there is less chance of forever getting stuck in a loop
You should declare Random outside of your loops otherwise you run the risk of just getting the same numbers ("randomly")
You reset the number to a new number after every guess so the user doesn't have a chance to guess the right number
With all this being said, I think the Math.Abs was correct if you are trying to find the distance away from the number.. I wouldnt use less than two though as that would mean only numbers that are 1 away from the answer are "hot"
Note: Answer is based off question revision #5
Update
Doesn't seem like you were far off but you still reset the number every loop
number = rndm.Next(10) + 1; //Insert here
do
{
//Displays the which round (out of 10) to the user
Console.WriteLine("Round" + roundcount);
guessesleft = 3; //The remaining guesses left for the user
do
{
// Remove this -- number = rndm.Next(10) + 1;

I think this is what you want,please try it:
static int guessesleft;
static Random ran = new Random();
static int MagicNumber;
static string UserInput;
static void Main(string[] args)
{
ConsoleKeyInfo ci = new ConsoleKeyInfo();
do
{
guessesleft = 3;
UserInput = "";
Console.Clear();
string username;
int guesscount = 1;
Console.WriteLine("Welcome to Jackie's Guessing Game!");
Console.WriteLine("");
Console.WriteLine("Please press any button to continue.");
Console.ReadLine();
Console.WriteLine("What's your name?");
username = (Console.ReadLine());
//If you're wondering at all, the "You must guess what it is inthree tries." is intentional, since it was showing double-spaced in the command prompt
Console.WriteLine("Well, " + username + ", I am thinking of a number from 1 to 10. You must guess what it is inthree tries.");
Console.WriteLine("");
MagicNumber = ran.Next(1, 11);
do
{
Console.WriteLine("Please insert your " + guesscount++ + "º guess!");
UserInput = Console.ReadLine().Trim();
if (UserInput == MagicNumber.ToString())
break;
if (Math.Abs(Convert.ToInt32(UserInput) - MagicNumber) < 2)
Console.WriteLine("Hot!!");
else if(Math.Abs(Convert.ToInt32(UserInput) - MagicNumber) < 3)
Console.WriteLine("Warm!!");
Console.WriteLine("No luck , you have " + --guessesleft + "º guesses left!");
Console.WriteLine();
} while (guesscount < 4);
if (guesscount == 4)
Console.WriteLine("Sorry " + username + " no more tries,you lost!");
else
Console.WriteLine("Congratulations your guess with number " + UserInput + " is correct,the number was " + MagicNumber);
Console.WriteLine("Press Q to quit or Enter to Play again!");
ci = Console.ReadKey();
} while (ci.Key != ConsoleKey.Q);
}