Develop Reference

How do I add a Y/N to Switch-Cases in C#?

I'm a complete Newbie to the world of programming, yet I really wish to learn a lot as quick as possible and now came up to a problem that I can't find to solute just via researching and "learning- by doing" (Trying around).
Basically I'm trying to work on a small console- based TextAdventure in C Sharp (With VisualStudios) Now I came to a Case- Switch (Offering the User some Options to read and walk through), but I wish to add a Y/N Confirmation in case the User decides to take a different path. For now it's only for the starting point of the story:
Does the User want to go into "The Wilds", "The City", "The Farm". Something as simple as that just in addition: "Are you sure (Y/N)?" leading the No to return the given choices.
Thank you all in advance and stay healthy!
Menu mainMenu = new Menu(prompt, options);
int selectedIndex = mainMenu.Run();
switch (selectedIndex)
{
case 0:
EnterTheWorld();
break;
case 1:
VisitTheMemorial();
break;
case 2:
TakeYourLeave();
break;
default:
break;
}
}
private void TakeYourLeave()
{
WriteLine("\nYou are about to take your leave... Are you sure ? (Y/N)");
ReadKey();
Environment.Exit(0);
}
private void VisitTheMemorial()
{
Clear();
//FILLER//
WriteLine("You may proceed by the press of any button.");
ReadKey(true);
RunMainMenu();
}
private void EnterTheWorld()
{
string prompt = "Where would you like to start your journey?";
string[] options = { "The Slums", "The Wilds", "The City", "The Farm" };
Menu startMenu = new Menu(prompt, options);
int selectedIndex = startMenu.Run();
BackgroundColor = ConsoleColor.White;
switch (selectedIndex)
{
case 0:
ForegroundColor = ConsoleColor.Black;
WriteLine("\n ||Small Description||Are you sure to take this path? (Y/N)");
break;
case 1:
ForegroundColor = ConsoleColor.Green;
WriteLine("\n ||Small Description||Are you sure to take this path? (Y/N)");
break;
case 2:
ForegroundColor = ConsoleColor.Red;
WriteLine("\n ||Small Description||Are you sure to take this path? (Y/N)");
break;
case 3:
ForegroundColor = ConsoleColor.Yellow;
WriteLine("\n ||Small Description|| Are you sure to take this path? (Y/N)");
break;
}

In this case, you need to take care of a few things:
Make sure that the entire switch-statement logic is in a while-loop, as such:
while (True) {
int selectedIndex = mainMenu.Run();
switch (selectedIndex)
{
case 0:
EnterTheWorld();
break;
case 1:
VisitTheMemorial();
break;
case 2:
TakeYourLeave();
break;
default:
break;
}
}
Check with your function if the input given is "No", if such, then immeditely return so your function exits before any navigation
private void VisitTheMemorial()
{
userInput = readKeyFunction();
if (userInput == "no") {
return;
}}
Finally, if the user doesn't select no, just do nothing and let the function go on

It is best to handle the 'Are you sure?' inside the menu.Run(), and return a value to the selectedIndex after the confirmation. Also avoid using while loop at the main flow in this case.
Note: you have to think in a modular way. Consider your Menu class as a module which handles user choice. The main flow does not have to bother about the confirmation by the user, it just have to process the final result of the user.
Another suggestion: Use enums instead of integers wherever possible for multiple choices.

breaking out a loop in c#

I am having trouble figuring out how to break out of a loop that contains a switch statement.
i need to press 0 twice to exit the console why?
how can i fix it to exit from the first time
public void Start()
{
int choice = 0;
bool trueNumber = false;
do
{
ShowMenu(); // display the menu
Console.Write("Your Choice : ");
trueNumber = int.TryParse(Console.ReadLine(), out choice);
if (!trueNumber)
Console.WriteLine("Your Choice must be an integer. Try again.");
switch (choice) // select the relevant function based on user input
{
case 1:
CalculateCelsiusToFahrenheit();
break;
case 2:
CalculateFahrenheitToCelsius();
break;
case 0:
return; // exit when i press 0
default:
Console.WriteLine("Invalid Option: Choose 0, 1, or 2 Thank you ");
break;
}
} while (choice != 0);
}

If you are running this from an IDE (like Visual Studio), the default behavior for console applications is to end with a "Press any key to continue." so it waits with the output displayed.
related answer: VS setting

Trying to make a menu that keeps repeating if the user enters something invalid

Total beginner here, literally started learning programming for the first time in my life yesterday, so please don't judge!
I'm trying to make a program that allows the user to enter the name and score of videogames, then show these scores upon request. I'm trying to make a menu. I noticed the program would crash if the user presses enter without entering any number, and I wanted to avoid that, but I'm stuck. If I press enter it doesn't crash. However, if I enter 1 or 2, the menu keeps going anyways, and if I press enter without entering anything after that, then it crashes? I'm lost.
namespace videogaems
{
class Program
{
static void Main(string[] args)
{
menu();
}
static void menu()
{
int option = 0;
Console.WriteLine("Select what you want to do: ");
Console.WriteLine("1- add game");
Console.WriteLine("2- show game rating");
bool tryAgain = true;
while (tryAgain)
{
try
{
while (option != 1 || option != 2)
{
option = Convert.ToInt32(Console.ReadLine());
tryAgain = false;
}
}
catch (FormatException)
{
option = 0;
}
}
}

Convert.ToInt32(Console.ReadLine()) will throw an exception if the string cannot be converted to an integer. Instead, you should use int.TryParse, which takes in a string and an out parameter that gets set to the converted value (if successful). It returns a bool which indicates if it was successful or not.
For example, the following code will loop as long as int.TryParse fails, and when it succeeds, userInput will contain the converted number:
int userInput;
while (!int.TryParse(Console.ReadLine(), out userInput))
{
Console.WriteLine("Please enter a whole number");
}
Another option, however, is to simply use Console.ReadKey(), which returns a ConsoleKeyInfo object that represents the key that the user pressed. Then we can just check the value of the key character (and ignore any keys that are invalid).
For example:
static void Menu()
{
bool exit = false;
while (!exit)
{
Console.Clear();
Console.WriteLine("Select what you want to do: ");
Console.WriteLine(" 1: Add a game");
Console.WriteLine(" 2: Show game rating");
Console.WriteLine(" 3: Exit");
ConsoleKeyInfo userInput = Console.ReadKey();
Console.WriteLine();
switch (userInput.KeyChar)
{
case '1':
// Code to add a game goes here (call AddGame() method, for example)
Console.Clear();
Console.WriteLine("Add a game was selected");
Console.WriteLine("Press any key to return to menu");
Console.ReadKey();
break;
case '2':
// Code to show a game rating goes here (call ShowRating(), for example)
Console.Clear();
Console.WriteLine("Show game rating was selected");
Console.WriteLine("Press any key to return to menu");
Console.ReadKey();
break;
case '3':
// Exit the menu
exit = true;
break;
}
}
}

Changing characters on the console depending on user keystrokes

What I want to do is to to change the console depending on what the user has pressed.
So I have a console with three options like this:
> Option 1
Option 2
Option 3
Basically, if the user presses the down arrow, the console becomes like this:
Option 1
> Option 2
Option 3
And if the user presses the up arrow, the console goes back to it's initial state.
I know how to read the user's input with Console.ReadKey(), but I don't know how to modify output that is already written.
One last thing is that when the user presses enter, the console does not create a new line, but chooses one of the options and calls a delegate.

This isn't too difficult to achieve using Console.ReadKey and some variables to hold the state of the selected option.
The following code is a very quick and lazy implementation of what you are looking for. Take the time to rewrite it yourself properly - this is to give you an idea of how you could achieve what you are looking for.
static void Main(string[] args)
{
bool IsRunning = true;
int Selected = 1;
while (IsRunning)
{
ConsoleKeyInfo NextKey = new ConsoleKeyInfo();
if (Selected < 1)
Selected = 3;
else if (Selected > 3)
Selected = 1;
Console.Clear();
if (Selected == 1)
Console.Write("> ");
Console.WriteLine("Option 1");
Console.WriteLine();
if (Selected == 2)
Console.Write("> ");
Console.WriteLine("Option 2");
Console.WriteLine();
if (Selected == 3)
Console.Write("> ");
Console.WriteLine("Option 3");
Console.WriteLine();
Console.Write("Choose an option (Q to Quit): ");
while (!(NextKey.Key == ConsoleKey.DownArrow ||
NextKey.Key == ConsoleKey.UpArrow ||
NextKey.Key == ConsoleKey.Q ||
(NextKey.KeyChar >= '1' &&
NextKey.KeyChar <= '3')))
{
NextKey = Console.ReadKey();
}
switch (NextKey.Key)
{
case ConsoleKey.D1:
// Do something
break;
case ConsoleKey.D2:
// Do something
break;
case ConsoleKey.D3:
// Do something
break;
case ConsoleKey.DownArrow:
Selected++;
break;
case ConsoleKey.UpArrow:
Selected--;
break;
case ConsoleKey.Q:
IsRunning = false;
break;
}
}
}
The code will loop whilst the 'Q' key has not been pushed to quit the application.
Pushing the down or up arrow will rotate through the options available.
Upon pushing 1, 2, or 3, you will cause the // Do something lines inside the switch statement to be run. You should here call whatever functionality exists for each of the options.
In order to update the 'menu' with the chosen option, the console output is cleared and then re-output. The correct option is identified via the Selected variable.
There are several other ways to implement the above, some much tidier. I wanted to give you an idea of where to start. I am not saying that this is the best or most tidy solution.
EDIT
A thought occurs - you wanted to use Enter to select the option.
I've modified the code a little to provide that functionality:
while (!(NextKey.Key == ConsoleKey.DownArrow ||
NextKey.Key == ConsoleKey.UpArrow ||
NextKey.Key == ConsoleKey.Q ||
NextKey.Key == ConsoleKey.Enter))
{
NextKey = Console.ReadKey();
}
switch (NextKey.Key)
{
case ConsoleKey.Enter:
// Do something depending on Selected option
switch (Selected)
{
case 1:
// Do something
break;
case 2:
// Do something
break;
case 3:
// Do something
break;
}
break;
case ConsoleKey.DownArrow:
...

Here's a similar approach with a little less code, which hides the cursor and shows our own custom cursor that indicates the selected menu item.
The method takes in a menu header, a list of options for the user to select from, and a cursor character. It prints out the header and an underline, and then each option with 3 spaces before each one. Then we move the cursor to the first option (row index 3 since the header is 0, underline is 1, and blank space is 2), second character, and write a backspace character followed by our cursor (the backspace erases the first character so we can write a new one).
As the user presses keys, we only handle the up and down arrows and the enter key. By passing true to Console.ReadKey(), the user input is "thrown away" and not displayed on the window. This allows us to switch on only the keys we care about.
When they press an arrow key we move the cursor to the second column in the current row, print a backspace and then a space (to erase the old cursor), then move up or down one row, and from the second column we print a backspace and then our cursor character.
When the user presses Enter, we enable the console cursor again and return the row that the cursor was on to indicate which item was selected at that time:
private static int GetMenuChoice(string header, List<string> options, char cursor = '>')
{
// Clear console and hide cursor
Console.Clear();
Console.CursorVisible = false;
// Write our header with an underline
Console.WriteLine(" " + header);
Console.WriteLine(" " + new string('-', header.Length));
Console.WriteLine();
// Write out each option with spaces before it
options.ForEach(option => Console.WriteLine($" {option}"));
// Move to the first option and, from the second character,
// write a backspace and then the cursor symbol
Console.SetCursorPosition(1, 3);
Console.Write($"\b{cursor}");
// Move cursor when user presses arrow keys, and get selection when they press enter
while (true)
{
// Pass 'true' to ReadKey so the input is not written
var input = Console.ReadKey(true);
switch (input.Key)
{
case ConsoleKey.UpArrow:
if (Console.CursorTop > 3)
{
Console.CursorLeft = 1;
Console.Write("\b ");
Console.SetCursorPosition(1, Console.CursorTop - 1);
Console.Write($"\b{cursor}");
}
break;
case ConsoleKey.DownArrow:
if (Console.CursorTop < options.Count + 2)
{
Console.CursorLeft = 1;
Console.Write("\b ");
Console.SetCursorPosition(1, Console.CursorTop + 1);
Console.Write($"\b{cursor}");
}
break;
case ConsoleKey.Enter:
var selection = Console.CursorTop - 3;
Console.CursorVisible = true;
Console.SetCursorPosition(0, options.Count + 4);
return selection;
}
}
}
This can be tested out with a sample ATM menu:
private static void Main()
{
var options = new List<string>
{
"Open a new account",
"Deposit Money",
"Withdraw money",
"Check balance",
"Exit"
};
var selectedItem = GetMenuChoice("ATM Machine", options);
Console.WriteLine($"You selected option: '{options[selectedItem]}'");
GetKeyFromUser("\nDone! Press any key to exit...");
}
Output

C# How do I make a switch ignore invalid input?

I am trying to make a simple console game that starts with a title screen. The user inputs 'N' for a new game, 'L' to load a game, or 'E' to exit. I have this set up as a switch, but I need to know how to make the program ignore any input other than the aforementioned keys. I've Googled this question but didn't find an answer. Please help if you can.
I don't see much point in posting the code as 10 lines of a simple switch probably wouldn't be terribly helpful to solving the problem. Also, if there would be an easier / more efficient way than a switch, I would love to know.
Thanks.

You can use a default: statement to handle the other (unknown) cases:
switch(inputString.ToLower())
{
case "n":
// Handle new
break;
//.. handle known cases
default:
Console.WriteLine("Unknown option chosen. Please enter valid option:");
// Re-read values, etc?
break;
}
Anything not specified in one of your other cases will fall into the default case, which you can then use to prompt for valid input.

If you want to actually ignore all keys other than valid ones you could do something like this:
public static char ReadKey(IEnumerable<char> validKeys)
{
var validKeySet = new HashSet<char>(validKeys);
while (true)
{
var key = Console.ReadKey(true);
if (validKeySet.Contains(key.KeyChar))
{
//you could print it out if you wanted.
//Console.Write(key.KeyChar);
return key.KeyChar;
}
else
{
//you could print an error message here if you wanted.
}
}
}
When you use ReadKey(true) the true indicated that it will intercept that key and not display it on the console. This gives you the option of determining if it's valid or invalid.

If a switch statement does not have a default block, and if the expression being switched on does not match any of the case blocks, the switch statement does nothing.

When you have only 3 cases, a switch isn't much more efficient than just a simple if-else construct.
if (input == "N")
{
// New game
}
else if (input == "L")
{
// Load game
}
else if (input == "E")
{
// Exit game
}
// if none of the cases match, the input is effectively ignored.
If you insist on using a switch, then your construct is very similar:
switch (input)
{
case "N":
//New Game
break;
case "L":
//Load Game
break;
case "E":
//Exit Game
break;
default:
//Do nothing (ignore unmatched inputs)
break;
}

Thanks for the replies, guys. I managed to solve the problem by doing the following:
static void titleInput()
{
ConsoleKeyInfo titleOption = Console.ReadKey(true);
switch (titleOption.Key)
{
case ConsoleKey.N:
Console.Clear();
break;
case ConsoleKey.L:
break;
case ConsoleKey.E:
Environment.Exit(0);
break;
default:
titleInput();
break;
}
}
I'm not sure how 'proper' this is, but it does what I need it to do. Any keys other than 'N', 'L', and 'E' no longer do anything.