How to rerun a code again in switch statement - c#

Objective: Request users to input yes or no again when they type "idk" until they reply yes or no, how to rerun the ask and ans above?
Requirement: Not to use boolean.
static void Main(string[] args)
{
string ask = "Yes or No?";
Console.WriteLine(ask);
string ans = Console.ReadLine();
switch(ans)
{
case "yes":
yes();
break;
case "no":
no();
break;
case "idk":
//run "ask" again
}
}

Hmmm.. Normally you would use booleans and loop while the boolean is still true and set it to false when you get what you want.
But if you want to avoid booleans you can use an infinite loop and just return out of the function you are in when you are done:
class Program
{
static void Main(string[] args)
{
string ask = "Yes or No?";
for (;;)
{
Console.WriteLine(ask);
string ans = Console.ReadLine();
switch(ans.ToLower())
{
case "yes":
yes();
return;
case "no":
no();
return;
}
}
}
static void yes() => Console.WriteLine("Yes selected");
static void no() => Console.WriteLine("No selected");
}

I will be suggesting you use a do-while loop rather then goto statment
static void Main(string[] args)
{
NotFound:
string ask = "Yes or No?";
Console.WriteLine(ask);
string ans = Console.ReadLine();
switch (ans)
{
case "yes":
yes();
break;
case "no":
no();
break;
case "idk":
goto NotFound;
}
}
private static void no()
{
}
private static void yes()
{
}

switch(exp)
{
case "+":
Console.WriteLine("Enter Yor Number");
int PlusA = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("Enter Yor Number");
int PlusB = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("Answer =");
Console.WriteLine(PlusA + PlusB);
One more question I want to make a plus calculator, I want to let the user type more then 2 numbers, until they type the symbol ; how to do that?

Related

How do I repeat a question in a switch case

I'm trying to make a question repeat if the input isn't right. Here's the code:
Console.WriteLine("choose a name");
string userInput = Console.ReadLine();
Boolean input = true;
switch (userInput)
{
case "joe":
Console.WriteLine("you chose a joe");
break;
case "bob":
Console.WriteLine("you chose a bob");
break;
}
How do I make it if it isn't one of the two answers it reasks the question?
Use the default case.
If none of the cases in a switch statement match, the default case runs.
Here's an example.
Console.WriteLine("choose a name");
string userInput = Console.ReadLine();
switch (userInput)
{
case "joe":
// ...
break;
case "bob":
// ...
break;
default:
// This runs if userInput is neither "joe" nor "bob"
}
Then you can make a method that writes choose a name to the console, takes the user's input, and runs the switch statement - and the default case would call the same method.
void GetName()
{
// Write "choose a name" to the console
// Take the user's input
switch (userInput)
{
case "joe":
// ...
break;
case "bob":
// ...
break;
default:
GetName();
return;
}
}
You need a loop (either while or do-while) to repeat the iteration but not a switch-case.
While switch-case is used to control the flag (isCorrectInput) that stops the loop.
bool isCorrectInput = false;
do
{
Console.WriteLine("choose a name");
string userInput = Console.ReadLine();
switch (userInput)
{
case "joe":
Console.WriteLine("you chose a joe");
isCorrectInput = true;
break;
case "bob":
Console.WriteLine("you chose a bob");
isCorrectInput = true;
break;
}
} while (!isCorrectInput);
Reference
Iteration statement
You should use a bool variable, that will determine whether you need to repeat the logic or not. Combine it with a loop and you get this:
bool keepAsking = true;
while (keepAsking)
{
Console.WriteLine("choose a name");
string userInput = Console.ReadLine();
Boolean input = true;
switch (userInput)
{
case "joe":
Console.WriteLine("you chose a joe");
keepAsking = false;
break;
case "bob":
Console.WriteLine("you chose a bob");
keepAsking= false;
break;
}
}
You can try something like this. BUt you need to slightly change your code.
class XYZ
{
static void Main(string[] args)
{
GetData()
}
}
static void GetData()
{
string userInput = Console.ReadLine();
checkcondition(userInput);
}
static void checkcondition(userInput)
{
switch (userInput)
{
case "joe":
Console.WriteLine("you chose a joe");
break;
case "bob":
Console.WriteLine("you chose a bob");
break;
default:
GetData();
break;
}
}
You can also achieve the same results using a smaller code but with a while loop instead of switch statement
while(true){
Console.Write("Choose a Name: ");
var name = Console.ReadLine().ToLower();
if(name == "joe" || name == "bob"){
Console.WriteLine("You chose a " + name + "!");
break;
}else{
Console.WriteLine("Invalid Selection, Try Again");
}
}

goto - not within scope (C#)

I am very new to code. Can anyone in a simple way explain why I cant use the goto statement like this, to make the code start over again? Or, how this could have been done in the correct way? And also, why I get an error message on the use of "static".
**
"No such label "Start" within the scope of the goto statmenet"
"The modifier static is not valid for this item"
using System;
namespace ConsoleApp3
{
class Program
{
static void Main(string[] args)
{
Start:
Random numberGenerator = new Random();
int num1 = numberGenerator.Next(1,11);
int num2 = numberGenerator.Next(1, 4);
Console.WriteLine("What is " + num1 + " times " + num2 + "?");
int svar = Convert.ToInt32(Console.ReadLine());
if (svar == num1 * num2)
{
Console.WriteLine("well done!");
}
else
{
int responseIndex = numberGenerator.Next(1, 4);
switch (responseIndex)
{
case 1:
Console.WriteLine("Wrong, try again? [Y or N]");
AskUser();
break;
case 2:
Console.WriteLine("The answer was incorrect");
AskUser();
break;
default:
Console.WriteLine("You can do better than that");
AskUser();
break;
}
static void AskUser() {
string jaellernei = Console.ReadLine().ToUpper();
if (jaellernei == "Y")
{
goto Start;
} else
{
return;
} }
}
}
}
}
Firstly, your AskUser method is incorrectly nested inside the other method - move it out.
Secondly: goto is only valid within a single method; you can jump around a single stack frame - you cannot jump between stack frames.
Thirdly: the number of times you should be using goto... well, it isn't quite zero, but it asymptotically approaches zero.
Don't use goto unless you MUST to !
and As #Marc Gravell said, it's valid within a single method.
Alternatively : you can make a method of the code u used in the Main method, and then call it from both, main method and the other method where you used goto statement.
Like :
using System;
namespace ConsoleApp3
{
class Program
{
static void Main(string[] args)
{
someFunction();
}
static void someFunction()
{
Random numberGenerator = new Random();
int num1 = numberGenerator.Next(1, 11);
int num2 = numberGenerator.Next(1, 4);
Console.WriteLine("What is " + num1 + " times " + num2 + "?");
int svar = Convert.ToInt32(Console.ReadLine());
if (svar == num1 * num2)
{
Console.WriteLine("well done!");
}
else
{
int responseIndex = numberGenerator.Next(1, 4);
switch (responseIndex)
{
case 1:
Console.WriteLine("Wrong, try again? [Y or N]");
AskUser();
break;
case 2:
Console.WriteLine("The answer was incorrect");
AskUser();
break;
default:
Console.WriteLine("You can do better than that");
AskUser();
break;
}
}
}
static void AskUser()
{
string jaellernei = Console.ReadLine().ToUpper();
if (jaellernei == "Y")
{
someFunction();
}
else
{
return;
}
}
}
}
You could do it like this
public static Random randd = new Random();
public static void FlachCards()
{
Start:
if (AskAUser() == "Y")
{
goto Start;
}
}
public static String AskAUser()
{
Console.WriteLine("Enter Y to play again");
return Console.ReadLine();
}

C# converting strings to int's

I'm new to c# and am trying to make a simple calculator.
It works fine until it goes back to the start to take a new number.
When taking the new number it says it cant convert the user input to a integer.
using System;
namespace simpleCalculator
{
class MainClass
{
public static void Main(string[] args)
{
start:
Console.Clear();
Console.WriteLine("Enter first number");
int x = Convert.ToConsole.ReadLine();
Console.WriteLine("Would you like to\n1. Add\n2. Multiply\n3. Devide");
string o = Console.ReadLine();
if (o == "1")
{
Console.WriteLine("Enter second number\n");
int y = Convert.ToInt32(Console.ReadLine());
add(temp, y);
goto start;
Console.Clear();
goto start;
}
}
public static void add(int num01, int num02)
{
Console.Clear();
Console.WriteLine((num01 + num02) + "\nPress enter to contiue.");
Console.Read();
}
}
}
Use TryParse so if the parsing fails, you will not get an exception.
var enteredValue = Console.ReadLine();
var parsedValue;
if (!int.TryParse(enteredValue, out parsedValue))
{
// parse failed do whatever you want
}
Do that for both entries and if both of them pass, then call your add method.
You're looking for int.Parse(). Be careful to validate your input. You should probably create an escape condition.
Edited to show an alternative solution
Edited to be more explicit on how to handle some input
class Program
{
public static void Main(string[] args)
{
string input = String.Empty;
int x = 0, y = 0;
while (true)
{
try
{
Console.WriteLine("Enter first number");
x = int.Parse(Console.ReadLine());
Console.WriteLine("Would you like to\n1. Add\n2. Multiply\n3. Divide");
input = Console.ReadLine();
Console.WriteLine("Please enter a second number");
y = int.Parse(Console.ReadLine());
}
catch
{
Console.WriteLine("Invalid input");
continue;
}
switch (input)
{
case "1":
Console.WriteLine($"{x} + {y} = " + add(x, y));
break;
case "2":
//TODO implement multiply case
break;
case "3":
//TODO implement divide case
break;
default:
Console.WriteLine("Invalid input");
break;
}
}
}
public static int add(int x, int y) => x + y;
}
Try this:
int numbers = Convert.ToInt32("1234");

Case Switch with a loop

I am not understanding what is going on in my case statement to determine if I want to redo the users input. Should I make another loop outside of my while loop? I attempted such and my case statement becomes unreachable code. Maybe I am not understanding case-switch statements.
class Program
{
static void Main(string[] args)
{
string _a = "";
constructor con = new constructor();
Console.WriteLine("Enter enter exit to end the program...");
Console.WriteLine("Enter C for constructor, M for method, A for an array...");
Console.WriteLine("Please reference source code to have full details and understanding...");
bool control = true;
while (control)
{
_a = Console.ReadLine();
switch (_a.ToUpper())
{
case "EXIT":
Console.WriteLine("Thank you for using AJ's program...");
control = false;
break;
case "C":
Console.WriteLine(con.a);
Console.WriteLine("Would you like to test another scenario?");
Console.ReadLine();
if (_a.ToUpper() == "Y")
{
Console.ReadLine();
return;
}
control = false;
break;
case "M":
control = false;
metroid();
break;
case "A":
control = false;
Array();
break;
default: Console.WriteLine("No match");
break;
}
}
}
public class constructor
{
public string a = "This is a constructor!";
}
static public void metroid()
{
string b = "This is a method!";
Console.WriteLine(b);
}
static public void Array()
{
try
{
Console.WriteLine("This is a random array. Please enter the size.");
string sSize = Console.ReadLine();
int arraySize = Convert.ToInt32(sSize);
int[] size = new int[arraySize];
Random rd = new Random();
Console.WriteLine();
for (int i = 0; i < arraySize; i++)
{
size[i] = rd.Next(arraySize);
Console.WriteLine(size[i].ToString());
}
}
catch (System.FormatException)
{
Console.WriteLine("Not correct format, restarting array process.");
Array();
}
}
}
}
Here's what I came up with. You had too many ways of exiting your loop, so I removed all of the control = false lines except where the user typed "EXIT"
Also, in case "C" you return out of the method if they choose "Y", I changed that to continue so that the loop would continue.
Finally, I moved the 3 instruction statements into the loop, so when the user hit "Y" it would print those again.
static void Main(string[] args)
{
string _a = "";
constructor con = new constructor();
bool control = true;
while (control)
{
Console.WriteLine("Enter enter exit to end the program...");
Console.WriteLine("Enter C for constructor, M for method, A for an array...");
Console.WriteLine("Please reference source code to have full details and understanding...");
_a = Console.ReadLine();
switch (_a.ToUpper())
{
case "EXIT":
Console.WriteLine("Thank you for using AJ's program...");
control = false;
break;
case "C":
Console.WriteLine(con.a);
Console.WriteLine("Would you like to test another scenario?");
_a = Console.ReadLine(); //<==problem #1 you didnt set your var name
if (_a.ToUpper() == "Y")
{
continue; //<==problem #2 return exits the program, continue, just keeps going
}
control = false;
break;
case "M":
metroid();
break;
case "A":
Array();
break;
default:
Console.WriteLine("No match");
break;
}
}
}
I think you should considering goto in this case. Yes you need to put some extra effort, but it will help you overcoming the While loop.
A sample below:
switch (_a.ToUpper())
{
case "EXIT":
Console.WriteLine("Thank you for using AJ's program...");
control = false;
// execute goto when your all line executes successfully
goto case "New";
case "New":
// some logic
}
See working sample here Goto-Switch
string NewInput= Console.ReadLine();
if (NewInput.ToUpper() == "Y")
{
//print some thing with console.writeline
//if after this you want to restart the loop then instead of return use
continue;
}
Try putting the Console.Writeline inside the while loop like this:
static void Main(string[] args)
{
bool control = true;
while (control)
{
Console.WriteLine("Enter enter exit to end the program...");
Console.WriteLine("Enter C for constructor, M for method, A for an array...");
Console.WriteLine("Please reference source code to have full details and understanding...");
string _a = Console.ReadLine();
switch (_a.ToUpper())
{
case "EXIT":
Console.WriteLine("Thank you for using AJ's program...");
control = false;
break;
case "C":
Console.WriteLine("press c");
Console.WriteLine("Would you like to test another scenario?");
Console.ReadLine();
if (_a.ToUpper() == "Y")
{
Console.ReadLine();
return;
}
control = false;
break;
case "M":
control = false;
metroid();
break;
case "A":
control = false;
Array();
break;
default: Console.WriteLine("No match");
break;
}
}
}
Additional reading about switch here and here.
Just add comment for the result, thanks. Hope this helped!
may be you want to change
Console.ReadLine();
if (_a.ToUpper() == "Y")
{
Console.ReadLine();
return;
}
as
_a = Console.ReadLine();
if (_a.ToUpper() == "Y")
{
_a = Console.ReadLine();
continue;
}

C# switch statement validation

I was wondering if there was a way to do something like this in C#:
some loop here
{
Console.WriteLine("Please enter a or b");
switch (Console.ReadLine().ToLower())
{
case "a":
//some code here
break;
case "b":
//some code here
break;
default:
Console.WriteLine("Error, enter a or b");
repeat loop
}
}
It's probably a stupid question but something like that would be greatly beneficial to my assignment.
Why not. Run a while loop that exists only when a or b is entered.
bool condition = false;
Console.WriteLine("Please enter a or b");
string str = string.Empty;
while (!condition)
{
str = Console.ReadLine().ToLower();
switch (str)
{
case "a":
//some code here
condition = true;
break;
case "b":
//some code here
condition = true;
break;
default:
Console.WriteLine("Error, enter a or b");
break;
}
}
Console.WriteLine("You have entered {0} ", str);
Console.ReadLine();
What about something like this?
var acceptedValues = new List<string>()
{
"a",
"b",
};
Console.WriteLine("Please enter {0}", string.Join("or", acceptedValues));
var enteredValue = string.Empty;
do
{
enteredValue = Console.ReadLine().ToLower();
} while (!acceptedValues.Contains(enteredValue));

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