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
Related
I am trying to make a console based application in which the program will subtract two random numbers from a range provided by the user but when i enter the values it give me a "Random min value cannot be greater than maxvalue" error
Here is my code
static void subtract()
{
bool tryagain = true;
while (tryagain == true)
{
Console.WriteLine("Choose a range of numbers");
Console.Write("First Value: ");
int firstval = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("First value: " + firstval);
Console.WriteLine("Second Value: ");
int secondval = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("Second value: " + secondval);
Console.WriteLine(firstval + secondval);
Random rnd = new Random();
int firstrndval = rnd.Next(firstval, secondval); //this line is throwing the error
int secondrndval = rnd.Next(firstval, secondval);
Console.WriteLine("What is " + firstrndval + "-" + secondrndval);
int potans;
potans = Convert.ToInt32(Console.ReadLine());
int ans = firstrndval - secondrndval;
if (ans != potans)
{
Console.WriteLine("Wrong Answer");
}
else
{
Console.WriteLine("Correct Answer");
}
Console.WriteLine("Would you like to try again Y/N");
string potbol = Console.ReadLine();
potbol = potbol.ToUpper();
if (potbol == "N")
{
tryagain = false;
}
}
}
I tried switching the values if the firstval is less than secondval but it would not work,i tried the tuple method and the three variable method but it didnt seem to work for me probably because it was in an if-else statement.I'm fairly new to C# and seem to not solve this problem.
First you must find the smaller number and the bigger number among the two:
int smaller = Math.Min(firstval, secondval);
int biggest = Math.Max(firstval, secondval);
int firstrndval = rnd.Next(smaller, biggest + 1);
int secondrndval = rnd.Next(smaller, biggest + 1);
You must put +1 on the second parameter because the second parameter is exclusive. That means, if you put rnd.Next(1,10) it will only return numbers among {1,2,3,4,5,6,7,8,9} (never 10).
You have two options
First : If the first number is greater than the second , swap them like this
if (firstval > secondval)
{
int temp = firstval;
firstval = secondval;
secondval = temp;
}
this will ensure that the firstVal will always be the greater one
Second Solution : Use the Math.Min() & Math.Max() functions like this
int firstrndval = rnd.Next(Math.Min(firstval, secondval), Math.Max(firstval, secondval));
int secondrndval = rnd.Next(Math.Min(firstval, secondval), Math.Max(firstval, secondval));
this will ensure that the minimum value from both variables will be at first whatever if it's the firstVal or the SecondVal & the same for the maxmimum value from both variables
I can't ever get guessLimit to equal 1, in the system log when I enter the limit of guesses as 5 and start guessing, the guessLimit will go down all the way to 2 and it will give me the "You Lose" message without letting me do my final guess... is there a reason for that?
public static void Main(string[] args){
string guess = "";
bool outOfguesses = false;
int guessCount = 0;
Console.Clear();
Console.Write("Enter the amount of guesses you want: ");
int guessLimit = Convert.ToInt32(Console.ReadLine());
Console.Clear();
Console.Write("Enter a word that will be guessed...: ");
string secretWord = Console.ReadLine();
Console.Clear();
Console.Write("You have " + guessLimit + " guesses" + "\nEnter a guess: ");
guess = Console.ReadLine();
while(guess.ToLower() != secretWord.ToLower() && !outOfguesses){
if(guessLimit >= guessCount || guessLimit == 1){
guessCount++;
guessLimit--;
Console.Write("\nWRONG! You have " + guessLimit + " guesses left." + "\nEnter another guess: ");
guess = Console.ReadLine();
} else{
outOfguesses = true;
}
}
if(outOfguesses == true){
Console.WriteLine("\nSorry...\nYou lose!");
} else{
Console.WriteLine("\nGood Job.\nYou Win!!");
}
Console.ReadLine();
}
When your if statement reaches
(Is 2 >= 3) this is false so it will skip over the if and go to the else
Which is why it stops there.
Also change your guesslimit ==1 to <1
I wrote a basic number guessing game from C#. It seems to return the 3rd option ("Wrong choice! Please try again.") every time no matter what var c is chosen by the user. I was trying with characters (s instead of 1 and w instead of 2 etc with c as a string) but it gave the same results. Not sure where it's going bad.
using System;
namespace Challanges
{
class Program
{
static int guess = 500;
static int low = 1;
static int high = 1000;
static bool cont = false;
static void Guess() //guesses and adjusts variables according to input.
{
int c;
Console.WriteLine("Is your number greater or less than: " + guess + Environment.NewLine + "If it is less than, press 1; if it is greater, press 2." + Environment.NewLine + "If it is your number, press 3.");
c = Convert.ToInt32(Console.Read());
if (c == 1)
{
high = 500;
guess = low + high / 2;
}
else if (c == 2)
{
low = 500;
guess = low + high / 2;
}
else if (c == 3)
{
Console.WriteLine("Congratulations!! We found your number!");
cont = true;
}
else
{
Console.WriteLine("Wrong choice! Please try again.");
Console.ReadKey();
}
}
static void Main(string[] args)
{
Console.WriteLine("Hello World!" + Environment.NewLine + "Let's play a guessing game. Think of a number between 1 and 1000." + Environment.NewLine + "Type your number :)");
int x = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("Your number is: " + x + Environment.NewLine + "Too easy?");
Console.ReadKey();
Console.WriteLine("Think of a number");
if(cont == false)
{
Guess();
} else
{
Console.ReadKey();
}
}
}
}
As mentioned in the comments before, Console.Read() returns a character code. The character code for the number 1 is 49, thus your conditions fail and the else block is executed.
What you wanted to do was use Console.ReadLine()which returns a string instead of character codes. If you cast that string into an Int32 you should be able to evaluate your conditions correctly.
The subject is a little problem:
Write a program and continuously ask the user to enter a number or "ok" to exit. Calculate the sum of all the previously entered numbers and display it on the console.
Here is my code:
var sum = 0;
while (true)
{
Console.WriteLine("Enter a number or ok to exit:");
if (Console.ReadLine() == "ok") break;
sum += Convert.ToInt32(Console.ReadLine());
Console.WriteLine(sum);
}
When I tap ok, it terminate.
When I tap number and enter, it shows system.formatexception:The input string is not in the correct format.
I know one of the solution is
var sum = 0;
while (true)
{
Console.Write("Enter a number (or 'ok' to exit): ");
var input = Console.ReadLine();
if (input.ToLower() == "ok")
break;
sum += Convert.ToInt32(input);
}
Console.WriteLine("Sum of all numbers is: " + sum);
Maybe My code looks a little weired, But Why is my code wrong?
Reason is input will be "ok". Can not convert that into an integer.
first you have to store the first input value into other variable.
then convert that string into integer and get summation.
var sum = 0;
while (true)
{
Console.Write("Enter a number (or 'ok' to exit): ");
var input = Console.ReadLine();
int newVariable = 0;
if (input.ToLower() != "ok")
{
newVariable = Convert.ToInt32(input);
}
input = Console.ReadLine();
if (input.ToLower() == "ok"){
break;
sum += newVariable;
}
}
Console.WriteLine("Sum of all numbers is: " + sum);
If there any problem here please let me know.
Try this:
var sum = 0;
while (true)
{
Console.WriteLine("Enter a number or ok to exit:");
String ans = Console.ReadLine();
if (ans == "ok" || ans.ToLower() == "ok") break;
sum += Convert.ToInt32(ans);
Console.WriteLine(sum);
}
Here I've just store input entered by user in one variable and use that variable in further process.
In your first code you have take input two times, first one is in IF condition and second in parsing, that may cause the problem.
The correct way to do this is to use int.TryParse for your conversion from a string to a number. TryParse attempts to convert the string to a number, but if it cannot do so (for example, the string contains more than just numeric digits) it will fail gracefully instead of causing an exception. The other answers so far will all cause an unhandled FormatException if something non-numeric is entered other than "ok". By using int.TryParse you can handle the case where it's a valid number, as well as the case where it is invalid, and then alert the user. Here's an example within the context of your code:
// I prefer using concrete types for numbers like this, so if anyone else
// reads it they know the exact type and numeric limits of that type.
int sum = 0;
int enteredNumber = 0;
while (true)
{
Console.Write("Enter a number (or 'ok' to exit): ");
var consoleInput = Console.ReadLine();
if (consoleInput.ToLower() == "ok")
break;
if(int.TryParse(consoleInput, out enteredNumber))
{
sum += enteredNumber;
}
else
{
Console.WriteLine("You entered '" + consoleInput + "', which is not a number.");
}
}
Console.WriteLine("Sum of all numbers is: " + sum.ToString());
This is better because you know you have no control over the user's input other than to validate it yourself, and so it's better to speculatively convert the number and be alerted to success or failure without triggering an exception. Wrapping everything with a try/catch block is not a proper solution.
Your first code example, as rightly pointed out in the comments, reads a line, tests it for 'ok', then throws it away, reads another line, and uses that to add to the sum, which is not what you wanted.
After some quick research, I would say the most concise way to handle this in C# is probably something like your second code example. In F# I was able to come up with the following examples (one is a loop, the other uses sequences, i.e. IEnumerable<_>s) but I found no concise way to get the same with C# and LINQ…
let inputLoop () =
let rec aux sum =
match stdin.ReadLine () with
| "ok" -> sum
| s -> aux (sum + int s)
stdout.WriteLine (aux 0 |> string)
let inputSeq () =
fun _ -> stdin.ReadLine ()
|> Seq.initInfinite
|> Seq.takeWhile (fun s -> s <> "ok")
|> Seq.sumBy int
|> string
|> stdout.WriteLine
Try it :)
var sum = 0;
while (true)
{
Console.Write("Enter a number: or ok to exit : ");
String input = Console.ReadLine();
if (input == "ok" || input.ToLower() == "ok") break;
if(string.IsNullOrWhiteSpace(input))
continue;
sum += Convert.ToInt32(input);
}
Console.WriteLine("Total Result: " + sum);
Write a program and continuously ask the user to enter a number or "ok" to exit. Calculate the sum of all the previously entered numbers and display it on the console. Happy Coding
var sum = 0;
while (true)
{
Console.Write("Write number or write \"ok\" for exit: ");
var input = Console.ReadLine();
if (input.ToLower() != "ok")
{
sum += Convert.ToInt32(input);
continue;
}
break;
}
Console.WriteLine("All sum: " + sum + ".");
This is one way to do it. I'm just learning to do this!
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Enter number to know the sum or press ok to exit and display the sum");
int sum = 0;
while (true) // to run the program continously asking user input
{
Console.WriteLine("Enter Number: ");
var input = Console.ReadLine(); // takes user input
if (input.ToLower() == "ok") // compares user input to string ok
break; //if user input is ok, breaks the loop and sum is displayed
var inputInInt = Convert.ToInt32(input); // if user input is int, continues to convert it to integer
sum += inputInInt; // user input in interger is added to sum
}
Console.WriteLine("The sum of entered numbers is: " + sum);
Console.ReadLine();
}
}
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);
}