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Validating input value from console without exiting loop C#

Lets say for a console application, I want the user to enter how many dices he would like to throw. Onlu values 1-5 will be accepted. I tried doing this:
Console.WriteLine("How many dices would you like to throw?");
int amount = Convert.ToInt32(Console.ReadLine());
while(true)
{
if(amount < 1 || amount > 5)
{
Console.WriteLine("Please enter a value between 1-5");
break;
}
}
The problem here is that if the user enters an invalid number, the program stops. I want it to simply continue asking until correct value is inputed. Any ideas?
cheers.

I haven't tested it but slightly refactored your code as below, it should do what you want:
Console.WriteLine("How many dices would you like to throw?");
int amount = Convert.ToInt32(Console.ReadLine());
while(amount < 1 || amount > 5)
{
Console.WriteLine("Please enter a value between 1-5");
amount = Convert.ToInt32(Console.ReadLine());
}
EDIT: if you want to safely check whether it is an integer value, you can use the below version of code:
Console.WriteLine("How many dices would you like to throw?");
var input = Console.ReadLine();
while(!int.TryParse(input, out int amount) || amount < 1 || amount > 5)
{
Console.WriteLine("Please enter a value between 1-5");
input = Console.ReadLine();
}

You might want to check if the entered value is actually an integer.
int amount;
Console.WriteLine("How many dices would you like to throw?");
do
{
if (int.TryParse(Console.ReadLine(), out var i))
{
if (i >= 1 && i <= 5)
{
amount = i;
break;
}
Console.WriteLine("The integer value is not between 1 and 5");
}
{
Console.WriteLine("The value you entered is not an integer");
}
} while (true);
EDIT
I generally like to give the user the option to exit completely.
int amount;
Console.WriteLine("How many dices would you like to throw? Or enter 'X' to exit.");
do
{
var input = Console.ReadLine();
if(input.Equals("X", StringComparison.InvariantCultureIgnoreCase))
{
return;
}
if (int.TryParse(input, out var i))
{
if (i >= 1 && i <= 5)
{
amount = i;
break;
}
Console.WriteLine("The integer value is not between 1 and 5");
}
{
Console.WriteLine("The value you entered is not an integer");
}
} while (true);

C# Sharp Grade program using for and while

I'm new at C# and am having trouble with nested loops. I'm working on a Grading program with a menu. The first menu asks the user how many grades would they like to enter. Then, the user enters the grades. The Second menu figures out the average and grade. I'm having trouble with a nested loop where it would ask you a given number of time to enter grades.
Once that is done, I'm also having trouble with how I would pass that info to the second menu to get the average. I done something like this better in Java, but there we had a set number of grades; then, we made a variable for each grade. Finally we summed them and divided by a set number.
bool exit = false;
do
{
Console.WriteLine("1. Enter Grades");
Console.WriteLine("2. Get Average");
Console.WriteLine("3. My program");
Console.WriteLine("4. exit");
string input = Console.ReadLine();
Console.WriteLine("");
if (input == "1")
{
int totalGrades = 0;
double grades;
double grade, finalGrade = 0;
//User Input
Console.WriteLine("How many grades do you want to enter? ");
//While loop for TryParse
while(!int.TryParse(Console.ReadLine(),out totalGrades))
{
Console.WriteLine("Please enter a valid number");
}
while (totalGrades < 1)
{
Console.WriteLine("Enter Grade: ");
string input = Console.ReadLine();
for (int i = 0; i<= totalGrades; totalGrades++)
Console.WriteLine(totalGrades);
}
Console.ReadLine();
}
else if (input == "2")
{
double average = 0;
if (average >= 90)
{
Console.WriteLine($"The average is a {average} which is an A.");
}
else if (average >= 80)
{
Console.WriteLine($"The average is a {average} which is an B.");
}
else if (average >= 70)
{
Console.WriteLine($"The average is a {average} which is an C.");
}
else if (average >= 60)
{
Console.WriteLine($"The average is a {average} which is an D.");
}
else
{
Console.WriteLine($"The average is a {average} which is an E.");
}
}
else
{
exit = true;
}
}
while (exit == false);

I've changed a few things in order to make the code easier to understand.
private static void Main(string[] args)
{
ProgramLoop();
}
private static void ProgramLoop()
{
var grades = new List<double>();
double average;
var exit = false;
do
{
System.Console.WriteLine("1. Enter Grades");
System.Console.WriteLine("2. Get Average");
System.Console.WriteLine("3. My program");
System.Console.WriteLine("4. exit");
var input = System.Console.ReadLine();
System.Console.WriteLine("");
switch (input)
{
case "1":
grades = EnterGrades();
break;
case "2":
average = GetAverage(grades);
break;
case "3":
MyProgram();
break;
case "4":
exit = true;
break;
default:
System.Console.WriteLine($"'{input}' is not a valid choice.");
break;
}
}
while (exit == false);
}
private static List<double> EnterGrades()
{
int numberOfGrades = 0;
var grades = new List<double>();
System.Console.WriteLine("How many grades do you want to enter? ");
// Read number of grades
while (!int.TryParse(System.Console.ReadLine(), out numberOfGrades) || numberOfGrades < 1)
{
System.Console.WriteLine("Please enter a valid number");
}
while (grades.Count != numberOfGrades)
{
// Read grade
System.Console.WriteLine("Enter Grade: ");
double grade;
while (!double.TryParse(System.Console.ReadLine(), out grade) || grade < 0 || grade > 100)
{
System.Console.WriteLine("Please enter a valid grade between 0.0 and 100.0");
}
grades.Add(grade);
}
return grades;
}
private static double GetAverage(IList<double> grades)
{
var average = grades.Average();
if (average >= 90)
{
System.Console.WriteLine($"The average is {average}, which is an A.");
}
else if (average >= 80)
{
System.Console.WriteLine($"The average is {average}, which is an B.");
}
else if (average >= 70)
{
System.Console.WriteLine($"The average is {average}, which is an C.");
}
else if (average >= 60)
{
System.Console.WriteLine($"The average is {average}, which is an D.");
}
else
{
System.Console.WriteLine($"The average is {average}, which is an E.");
}
return average;
}
I would recommend you to split your code into methods. The code will be easier to understand, and it's a great practice to not cram too much code together.
If you plan on adding more functionality and write more code, I would also recommend you to look into how you can apply object oriented programming to this, i.e. writing classes like a GradeCard.

So there are a couple things I'd like to highlight and I also added notes to the code. You want to keep 2 variables throughout your program/method to keep track of everything entered. They are the 2 pieces of average (1) Total and (2) Count of input numbers. See the code and read it line by line and see the comments. Hope this helps you. Feel free to ask questions if something doesn't make sense.
bool exit = false;
// added variables outside of loop so they are available everywhere in the method
double grades = 0;
int gradesCount = 0;
do
{
Console.WriteLine("1. Enter Grades");
Console.WriteLine("2. Get Average");
Console.WriteLine("3. exit");
string input = Console.ReadLine();
Console.WriteLine("");
if (input == "1")
{
int totalGrades = 0;
//User Input
Console.WriteLine("How many grades do you want to enter? ");
//While loop for TryParse
while (!int.TryParse(Console.ReadLine(), out totalGrades))
{
Console.WriteLine("Please enter a valid number");
}
// increment the count of grades by the number of grades the user wants to add
gradesCount += totalGrades;
// variable to keep a count and avoid infinite loop
int addedGradesCount = 0;
// while loop works like a for loop using our variable to keep count of grades we add
while (addedGradesCount < totalGrades)
{
Console.WriteLine("Enter Grade: ");
// variable to store entered grade
double newGrade = 0;
//Reusing code from while loop above for TryParse
while (!double.TryParse(Console.ReadLine(), out newGrade))
{
Console.WriteLine("Please enter a valid number");
}
// increment running total of grades with the user input number
grades += newGrade;
// output to user - got rid of loop through totalGrades
Console.WriteLine("You entered: " + newGrade + " - Total: " + grades);
// increment variable to keep count! if this is not here, you will have infinite loop
addedGradesCount++;
}
// Console.ReadLine(); // not needed
}
else if (input == "2")
{
// calculate average using the method variables we initialized at the beginning
double average = (grades / gradesCount);
if (average >= 90)
{
Console.WriteLine($"The average is a {average} which is an A.");
}
else if (average >= 80)
{
Console.WriteLine($"The average is a {average} which is an B.");
}
else if (average >= 70)
{
Console.WriteLine($"The average is a {average} which is an C.");
}
else if (average >= 60)
{
Console.WriteLine($"The average is a {average} which is an D.");
}
else
{
Console.WriteLine($"The average is a {average} which is an E.");
}
}
else
{
exit = true;
}
} while (exit == false);
Console.ReadKey();

this seems to work
static void Main(string[] args)
{
bool exit = false;
List<float> grades = new List<float>();
do
{
Console.WriteLine("1. Enter Grades");
Console.WriteLine("2. Get Average");
Console.WriteLine("3. My program");
Console.WriteLine("4. exit");
Console.WriteLine("");
string input = Console.ReadLine();
Console.WriteLine("");
if (input == "1")
{
int totalGrades = 0;
//User Input
Console.WriteLine("How many grades do you want to enter? ");
while (true)
{
try
{
totalGrades = Convert.ToInt32(Console.ReadLine());
break;
}
catch (FormatException)
{
Console.WriteLine("This is not a valid number");
continue;
}
}
Console.WriteLine("");
while (totalGrades > 0)
{
while (true)
{
try
{
grades.Add(Convert.ToInt32(Console.ReadLine()));
totalGrades--;
break;
}
catch (FormatException)
{
Console.WriteLine("This is not a valid number");
continue;
}
}
}
Console.WriteLine("");
}
else if (input == "2")
{
double average = grades.Average();
if (average >= 90)
{
Console.WriteLine($"The average is a {average} which is an A.");
}
else if (average >= 80)
{
Console.WriteLine($"The average is a {average} which is an B.");
}
else if (average >= 70)
{
Console.WriteLine($"The average is a {average} which is an C.");
}
else if (average >= 60)
{
Console.WriteLine($"The average is a {average} which is an D.");
}
else
{
Console.WriteLine($"The average is a {average} which is an E.");
}
Console.WriteLine("");
}
else if (input == "4")
{
exit = true;
} else
{
Console.WriteLine("This is not an option");
}
}
while (exit == false);
}

Break loops using while statement

I am writing a C# program that prints "true" if number <= 20 and "false" if number > 20 using a while loop but the program keeps on executing.
I want to break the program if it reaches certain number e.g. number > 26.
The code for the program is:
public static void Main()
{
Console.WriteLine("Please enter a number");
int numnber = Convert.ToInt32(Console.ReadLine());
while (numnber <= 20)
{
Console.WriteLine("True");
Console.ReadLine();
int number1 = numnber++;
while (numnber > 20)
{
Console.WriteLine("False");
Console.ReadLine();
}
}
}

you can just use break; Try this:
Console.WriteLine("Please enter a number");
int numnber = Convert.ToInt32(Console.ReadLine());
while (numnber <= 20)
{
Console.WriteLine("True");
Console.ReadLine();
int number1 = numnber++;
while (numnber > 20)
{
Console.WriteLine("False");
Console.ReadLine();
}
break;
}
But this programming is not good at all because you are breaking loop after all for this simply you can use if else like this..
Console.WriteLine("Please enter a number");
int numnber = Convert.ToInt32(Console.ReadLine());
if(numnber <= 20)
{
Console.WriteLine("True");
}
else
{
Console.WriteLine("False");
}

According to your description, your major issue should be
the program keeps on executing
However, it's not going to reach 26 as #King King mentioned.
It stuck inside the inner while which should be replaced by if condition.
Lastly, if you have to exec the number check at least one time you can use do while
do
{
if (numnber <= 20)
{
Console.WriteLine("True");
}
else if (numnber > 20)
{
Console.WriteLine("False");
}
numnber++;
Console.WriteLine("number: {0}", numnber);
} while (numnber < 26);
Console.ReadLine();

Thank you all but the solution to the problem would be. The code is as follows:
public static void Main()
{
int number;
do
{
Console.WriteLine("Please enter a number");
number = Convert.ToInt32(Console.ReadLine());
do
{
Console.WriteLine("True value. True value is supplied");
Console.ReadLine();
number++;
while (number >= 21 && number < 27)
{
Console.WriteLine("False value. False value is supplied");
Console.ReadLine();
number++;
}
} while (number <= 20);
} while (number > 27);
}

C# guessing game with only X tries [closed]

Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 6 years ago.
Improve this question
This is basically my first little C# program. I built in a "rule" so you only have 20 tries to guess the correct number. I was wondering if there is a more beautiful way to implement this "rule".
This is my code:
bool run = true;
while (run == true) // Main While Schleife
{
Random rndnr = new Random();
int rnd;
rnd = rndnr.Next(1, 100);
int guess;
int trys;
trys = 0;
guess = 0;
Console.WriteLine("Can you guess my number? I am thinking about a number between 1 and 100!");
guess = Convert.ToInt32(Console.ReadLine());
Console.WriteLine(rnd);
while (guess != rnd)
{
if (trys > 20)
{
Console.Clear();
Console.WriteLine("You only have 20 trys. You failed! \n");
run = false;
Console.WriteLine("Do you wann play again? Press R + Enter to play again!");
string rerun = Console.ReadLine().ToUpper();
if (rerun == "R")
{
run = true;
trys = 0;
Console.Clear();
break;
}
else
{
run = false;
break;
}
}
if (guess > rnd)
{
Console.WriteLine("My number is lower than" + guess + "\n guess again >>");
guess = Convert.ToInt32(Console.ReadLine());
}
if (guess < rnd)
{
Console.WriteLine("My number is higher than" + guess + "\n guess again >>");
guess = Convert.ToInt32(Console.ReadLine());
}
if (guess == rnd)
{
Console.Write("You guessed right my number is" + rnd + "and you needed " + trys + "trys");
run = false;
Console.WriteLine("Do you wann play again? Press R + Enter to play again!");
string rerun = Console.ReadLine().ToUpper();
if (rerun == "R")
{
run = true;
trys = 0;
Console.Clear();
}
else
{
run = false;
break;
}
}
trys++;
}
}
Console.Clear();
Console.WriteLine("Thanks for palying see you next time!");
Console.ReadLine();
}
}

I made a few bug fixes and generally tried to improve the code a bit. Hope you find it helpful:
bool run = true;
int maxTrys=20;
Random random = new Random();
while (run)
{
int rnd=random.Next(1, 101);
Console.WriteLine("Can you guess my number? I am thinking about a number between 1 and 100!");
int trys=0;
bool solved=false;
while (!solved && trys<maxTrys)
{
trys++;
int guess;
bool numericGuess;
do {
numericGuess=int.TryParse(Console.ReadLine(), out guess);
if (!numericGuess) {
Console.WriteLine("Please enter a number");
}
} while (!numericGuess);
if (guess > rnd)
{
Console.WriteLine(string.Format("My number is lower than {0}\n guess again >>", guess));
}
else if (guess < rnd)
{
Console.WriteLine(string.Format("My number is higher than {0}\n guess again >>", guess));
}
else if (guess == rnd)
{
solved=true;
Console.WriteLine(string.Format("You guessed right my number is {0} and you needed {1} trys", rnd, trys));
}
}
if (!solved) {
Console.Clear();
Console.WriteLine(string.Format("You only have {0} trys. You failed! \n", maxTrys));
}
Console.WriteLine("Do you wanna play again? Press R + Enter to play again!");
string rerun = Console.ReadLine().ToUpper();
if (!rerun.Equals("R"))
{
run = false;
}
}
Console.Clear();
Console.WriteLine("Thanks for playing see you next time!");
Console.ReadLine();

Random r = new Random();
int secretNumber = r.Next(1, 11);
int i = 0;
int chance = 5;
Console.WriteLine("Game: guess number");
while (i < chance)
{
Console.WriteLine("Your turn");
if (secretNumber == int.Parse(Console.ReadLine()))
{
Console.WriteLine("You won!");
break;
}
i++;
}
if (i == chance)
{
Console.WriteLine("You lost!");
Console.WriteLine("The secret number is " + secretNumber);
}
Simple way

Highest Common Factor C#

I have the current coding and I feel as if it is close to what I need but I can't seem to get it to work for what I want. I am trying to get it to output the highest common factor of the two numbers entered.
i = myInt;
{
if (myInt % i == 0 && myInt2 % i == 0)
{
Console.Write("Your GCF is...");
Console.Write("{0} ", i);
Console.ReadLine();
}
else
i--;
goto;
}

As others said in comments, you should really avoid goto statements because they are bad practice, especially when you are learning your college course of programming (that usually should conform to structural programming). Instead use while loop (or any other) with two conditions as you can see in the example. Also, I think that you should start your search from the smaller number (the first entered does not need to be smaller one) which is a little improvement in terms of performance. This is the code:
static void Main(string[] args)
{
string myInput;
int myInt;
string myInput2;
int myInt2;
int i;
Console.Write("Please enter a number: ");
myInput = Console.ReadLine();
myInt = Int32.Parse(myInput);
Console.Write("Please enter another number: ");
myInput2 = Console.ReadLine();
myInt2 = Int32.Parse(myInput2);
i = myInt > myInt2 ? myInt2 : myInt;
bool found = false;
while(!found && i>0)
{
if (myInt % i == 0 && myInt2 % i == 0)
{
Console.Write("Your GCF is...");
Console.Write("{0} ", i);
Console.ReadLine();
found = true;
}
else
i--;
}
}
EDIT: I included the other possible solution thanks to #Servy
bool found = false;
for( i = Math.Min(myInt, myInt2); !found && i>0; i--)
{
if (myInt % i == 0 && myInt2 % i == 0)
{
Console.Write("Your GCF is...");
Console.Write("{0} ", i);
Console.ReadLine();
found = true;
}
}

{
label:
if (myInt % i == 0 && myInt2 % i == 0)
{
Console.Write("Your GCF is...");
Console.Write("{0} ", i);
Console.ReadLine();
}
else
i--;
goto label;
}
will do. However, this is a very bad idea. Rather learn how to use while.