i'm trying to make this method like, if you haven't pressed the correct value a message box will show and when you press the messagebox it will return and you have to try to put the rigth values in again and so on. And if the field is null or empty is has to give =0.. If i press ex. e2 it has to pup up with the message box??
have tried this one without the else if.. and the messagebox vil not disappear? please help
public int playerOneDart1Value;
public int calculateDart1()
{
if (player == "t1" || player == "T1" || player == "3")
{
playerOneDart1Value = 3;
}
else if (player == null) or empty??
{
playerOneDart1Value = 0;
}
else
{
MessageBox.Show("not valid input");
return calculateDart1();
}
return playerOneDart1Value;
}
You're calling return calculateDart1(); straight after showing the message box, so the user never has a chance to alter the input, before the check being made again, and showing the message box.
You are calling the function calculateDart1 recursively and so the reason the messagebox won't disappear is that MessageBox.Show("not valid input"); is being called over and over again.
You're calling calculateDart1() right after the MessageBox prompt which results in an endless loop which makes the user unable to provide new input. For your "null or empty" requirement, you can use string.IsNullOrEmpty which returns true if a string is either null or empty.
public int playerOneDart1Value;
public int calculateDart1()
{
if (string.IsNullOrEmpty(player))
{
playerOneDart1Value = 0;
}
else if (player == "t1" || player == "T1" || player == "3")
{
playerOneDart1Value = 3;
}
else
{
MessageBox.Show("not valid input");
//you can use something like a negative value to indicate invalid input
playerOneDart1Value = -1;
}
return playerOneDart1Value;
}
Related
So I have a bool method that checks if the user has a club membership, then I have another bool method which is supposed to tell what's supposed to be printed if the user does have a membership and play the little game to check if the user wins a prize. The problem is, when I run the program it prints out the "Welcome to the VIP only, sir." twice and skips the rest of the code, so what can I do to fix this issue.
static void Main(string[] args)
{
LoyaltyDiscount();
EnterContest(RandomClass);
}
private static bool LoyaltyDiscount()
{
string input;
Write("\nAre you a member of our Futility Club frequent shopper program? ('Y' if yes) ");
input = ReadLine().ToUpper();
if(input == "YES" || input == "Y")
{
//if user does have a club membership
WriteLine("Welcome to the VIP only, sir.");
return true;
}
else
{
//if user does not have a club membership
WriteLine("Thats okay, we still appreciate your purchase.");
return false;
}
}
private static bool EnterContest(Random chanceGenerator)
{
string input = LoyaltyDiscount().ToString();
int randomNumber;
const int gameMin = 1;
const int gameMax = 10;
Random RandomClass = new Random();
randomNumber = RandomClass.Next(gameMin, gameMax);
if ((input == "YES") || (input == "Y"))
{
//prompt if user answers "yes" to if they a club membership and ask to play the game
Write("Do you want to play a game and win a prize?");
int.TryParse(ReadLine(), out int guess);
if (guess < gameMin || guess > gameMax)
{
//if user guesses number out of boundary
WriteLine("Guess out of boundary");
return false;
}
if (guess == randomNumber)
{
//if user guesses correct number
WriteLine("Correct guess.");
}
else
{
//if user guesses wrong number
Write("Wrong guess.");
return false;
}
}
return true;
}
The goal is to get the user input from LoyaltyDiscount() method and ask if the user does have a membership, then if the user does have a membership, use it in EnterContest() method only if they have a membership.
You calling LoyaltyDiscount() method in two places once in main method then in EnterContest() method. that's the reason it prints two times.
1. you called the method 'LoyaltyDiscount()' for first time here.
static void Main(string[] args)
{
LoyaltyDiscount();
EnterContest(RandomClass);
}
Then you called it again here. That's why it printed the sentence twice.
private static bool EnterContest(Random chanceGenerator)
{
string input = LoyaltyDiscount().ToString();
.
.
}
2. The return value of this method 'LoyaltyDiscount()' is bool, and it was transformed to string type to be 'True' or 'False'. if you print the result of LoyaltyDiscount().Tostring() you will see what happened.
string input = LoyaltyDiscount().ToString();
...Omit some codes...
Console.WriteLine(input);//it will be either 'True' or 'False'
//So here you could change the 'if' condition to be like this:
//if (input=="True")
if ((input == "YES") || (input == "Y"))
{
.......
}
I am a complete newbie and i am stuck on a small problem
I want the user to only be able to have yes or no as an answer.
This is what I came up with
static public bool askBool(string question)
{
try
{
Console.Write(question);
return Console.ReadLine() == "y";
}
catch (Exception)
{
throw new FormatException("Only y or n Allowed");
}
}
The problem is entering any other letter then 'y' will result in false, how can I best solve this ?
Thank you in advance.
EDIT (from comment question)
try
{
Console.Write(question);
return int.Parse(Console.ReadLine());
}
catch (Exception)
{
throw new FormatException("Please Enter a Number");
}
I doubt if you want an exception to be thrown - there's nothing exceptional if the user puts OK instead of yes; I suggest to keep asking until "yes" or "no" are read:
public static AskBool(string question) {
while (true) {
// If we have a question to ask (the question is not empty one)...
if (!string.IsNotNullOrWhiteSpace(question))
Console.WriteLine(question); // ... ask it
// Trim: let be nice and trim out leading and trailing white spaces
string input = Console.ReadLine().Trim();
// Let's be nice and accept "yes", "YES", "Y" etc.
if (string.Equals(input, "y", StringComparison.OrdinalIgnoreCase) ||
string.Equals(input, "yes", StringComparison.OrdinalIgnoreCase))
return true;
else if (string.Equals(input, "n", StringComparison.OrdinalIgnoreCase) ||
string.Equals(input, "no", StringComparison.OrdinalIgnoreCase))
return false;
// In case of wrong user input, let's give a hint to the user
Console.WriteLine("Please, answer yes or no (y/n)");
}
}
Here the method will only return true or false if user has entered true or false.If user enters any word the loop will just continue to ask him for input until he enters y or n
you can give it a try by doing following changes
static public bool askBool(string question)
{
bool boolToReturn = false;
Console.Write(question);
while (true)
{
string ans = Console.ReadLine();
if (ans != null && ans == "y")
{
boolToReturn = true;
break;
}
else if ( ans != null && ans == "n")
{
boolToReturn = false;
break;
}
else
{
Console.Write("Only y or n Allowed");
}
}
return boolToReturn;
}`
Answer to second question:-
`
public static int askInt(string question)
{
Int intToReturn = false;
Console.Write(question);
while (true)
{
string ans = Console.ReadLine();
if (int.TryParse(and,out intToreturn))
break;
else
Console.Write("Only number Allowed");
}
return intToReturn;
}`
A bit more simplified version of Dmitry's answer with switch (what I normally do for this kind of scenarios):
static public bool askBool(string question)
{
while(true)
{
Console.Clear();
Console.Write(question);
var input = Console.ReadLine().Trim().ToLowerInvariant();
switch (input)
{
case "y":
case "yes": return true;
case "n":
case "no": return false;
}
}
}
Also I'd consider changing .ReadLine() to .ReadKey() because what we really need here is just 'y' or 'n'... One key is enough.
We use Exceptions mostly for scenarios when unexpected value will lead to some error. We don't throw an exception when we expect user to enter rubbish values and handle them.
You want to throw the exception, not catch it. Example:
static public bool askBool(string question)
{
Console.Write(question);
var input = Console.ReadLine();
if (input == "y")
{
return true;
}
else if(input == "n")
{
return false;
}
else//It's not y or n: throw the exception.
{
throw new FormatException("Only y or n Allowed");
}
}
Of course, you must then capture the 'FormatException' where you call this method.
Something like this?
if (Console.ReadLine() == "y")
{
return true;
}
else if (Console.ReadLine() == "n")
{
return false;
}
else {
throw new Exception("only y and n allowed...");
}
Here another idea:
public static bool ReadUserYesOrNo()
{
bool userSaysYes = true;
Console.Write("Y\b");
bool done = false;
while (!done)
{
ConsoleKeyInfo keyPressed = Console.ReadKey(true); // intercept: true so no characters are printed
switch (keyPressed.Key) {
case ConsoleKey.Y:
Console.Write("Y\b"); // print Y then move cursor back
userSaysYes = true;
break;
case ConsoleKey.N:
Console.Write("N\b"); // print N then move cursor
userSaysYes = false;
break;
case ConsoleKey.Enter:
done = true;
Console.WriteLine();
break;
}
}
return userSaysYes;
}
This will print the default value Y to the console. By pressing Y or N the user can toggle between the two values. The character in the console output will be overwritten. Pressing 'enter' selects the choice and the method returns the result.
I'm having some trouble with my console application.
I want to check the user input and execute something depending on what the user wrote. My code looks something like this:
if(Console.ReadLine() == "ADD")
{
//Add
}
else if (Console.ReadLine() == "LIST")
{
//DisplayList
}
else if (Console.ReadLine() == "SORT")
{
//Sort
}
else
{
//DisplayErrorMsg
}
Now when i type LIST in the console, i get a line-break, and I have to type LIST again to get expected behaviour, and all following else-if statements just add another line-break. (example below)
I've looked everywhere I can but I can't see what I've done wrong...
Please help!
SORT
SORT
SORT
//Sorting...
You are invoking ReadLine multiple times and therefore you read multiple times from the stdin. Try the following:
var line = Console.ReadLine();
if (line == "ADD")
{
//Add
}
else if (line == "LIST")
{
//DisplayList
}
else if (line == "SORT")
{
//Sort
}
else
{
//DisplayErrorMsg
}
Try to get line in a string, and so test the string.
string line = Console.ReadLine();
if (line == "ADD")
{
//Add
}
else if (line == "LIST")
{
//DisplayList
}
else if (line == "SORT")
{
//Sort
}
else
{
//DisplayErrorMsg
}
Every time you call Console.ReadLine() it will wait for user input.
Assign the value returned from running Console.ReadLine() to a variable.
Then do your if, else checks on that variable.
var userInput = Console.ReadLine();
if(userInput == "ADD")
{
//Add
}
else if (userInput == "LIST")
{
//DisplayList
}
else if (userInput == "SORT")
{
//Sort
}
else
{
//DisplayErrorMsg
}
string readfromConsole = Console.ReadLine()
if(readfromConsole == "ADD")
{
//Add
}
else if (readfromConsole == "LIST")
{
//DisplayList
}
else if (readfromConsole == "SORT")
{
//Sort
}
else
{
//DisplayErrorMsg
}
The problem you are having is that Console.readLine does exactly what it says it reads a new line. So what this change does is it saves the first read and compares against that instead of reading a new line each time. I hoped this helped
I am done with this problem(using an alternative method). But still don't know why the following method is not working. Please help
Aim: when leave from a text box
check whether it contain only digits-then allow to leave.
If not show an error provider.
check whether string length is not more than 7 and not 0 -then allow to leave.
if not show an error provider.
Code that doesn't seem working is given below! :
private void textBox24_Validating(object sender, CancelEventArgs e)
{
bool result = true;
foreach (char y in textBox24.Text)
{
while (y < '0' || y > '9')
result = false;
}
if (result == false)
{
errorProvider4.SetError(textBox24, "Enter digits only");
textBox24.Focus();
}
else if (textBox24.Text.Length == 0)
{
errorProvider4.SetError(textBox24, "Enter the value");
textBox24.Focus();
}
else if (textBox24.Text.Length > 7)
{
errorProvider4.SetError(textBox24, "Maximum length is 7 digits");
textBox24.Focus();
}
else
errorProvider4.Clear();
}
problem with this code:
when I enter input other than digits, it gets stuck.
May be this wont be a big question. However help me.
code that now I am using:
private void textBox24_Validating(object sender, CancelEventArgs e)
{
int check = 123;
bool result = int.TryParse(textBox24.Text, out check);
if (result == false)
{
errorProvider4.SetError(textBox24, "Only digits are allowed");
textBox24.Focus();
}
else if (textBox24.Text.Length > 7)
{
errorProvider4.SetError(textBox6, "Invalid value");
textBox24.Focus();
}
else
errorProvider4.Clear();
}
inside while loop you have condition if true you set the result as true but loop running forever because condition again true.
foreach (char y in textBox24.Text)
{
while (condition) // this is run forever if true
result = false;
}
you can use break; if true case like below
foreach (char y in textBox24.Text)
{
while (condition){
result = false;
break;
}
}
Few more Suggestion..
TextBox control having property called MaxLength you can set it as 7 to limit user input up to 7 characters
if you need to allow only digits don't use int.TryParse method. if input with decimal points will pass the validation.
to check string contains only digits you can use code like if (textBox1.Text.ToCharArray().Any(c=>!Char.IsDigit(c)))
if validation fail you need to set e.Cancel = true;
I have created a form-based program that needs some input validation. I need to make sure the user can only enter numeric values within the distance Textbox.
So far, I've checked that the Textbox has something in it, but if it has a value then it should proceed to validate that the entered value is numeric:
else if (txtEvDistance.Text.Length == 0)
{
MessageBox.Show("Please enter the distance");
}
else if (cboAddEvent.Text //is numeric)
{
MessageBox.Show("Please enter a valid numeric distance");
}
You may try the TryParse method which allows you to parse a string into an integer and return a boolean result indicating the success or failure of the operation.
int distance;
if (int.TryParse(txtEvDistance.Text, out distance))
{
// it's a valid integer => you could use the distance variable here
}
If you want to prevent the user from enter non-numeric values at the time of enter the information in the TextBox, you can use the Event OnKeyPress like this:
private void txtAditionalBatch_KeyPress(object sender, KeyPressEventArgs e)
{
if (!char.IsDigit(e.KeyChar)) e.Handled = true; //Just Digits
if (e.KeyChar == (char)8) e.Handled = false; //Allow Backspace
if (e.KeyChar == (char)13) btnSearch_Click(sender, e); //Allow Enter
}
This solution doesn't work if the user paste the information in the TextBox using the mouse (right click / paste) in that case you should add an extra validation.
Here is another simple solution
try
{
int temp=Convert.ToInt32(txtEvDistance.Text);
}
catch(Exception h)
{
MessageBox.Show("Please provide number only");
}
You can do it by javascript on client side or using some regex validator on the textbox.
Javascript
script type="text/javascript" language="javascript">
function validateNumbersOnly(e) {
var unicode = e.charCode ? e.charCode : e.keyCode;
if ((unicode == 8) || (unicode == 9) || (unicode > 47 && unicode < 58)) {
return true;
}
else {
window.alert("This field accepts only Numbers");
return false;
}
}
</script>
Textbox (with fixed ValidationExpression)
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:RegularExpressionValidator ID="RegularExpressionValidator6" runat="server" Display="None" ErrorMessage="Accepts only numbers." ControlToValidate="TextBox1" ValidationExpression="^[0-9]*$" Text="*"></asp:RegularExpressionValidator>
I agree with Int.TryParse but as an alternative you could use Regex.
Regex nonNumericRegex = new Regex(#"\D");
if (nonNumericRegex.IsMatch(txtEvDistance.Text))
{
//Contains non numeric characters.
return false;
}
You can do this way
// Check if the point entered is numeric or not
if (Int32.TryParse(txtEvDistance.Text, out var outParse))
{
// Do what you want to do if numeric
}
else
{
// Do what you want to do if not numeric
}
I have this extension which is kind of multi-purpose:
public static bool IsNumeric(this object value)
{
if (value == null || value is DateTime)
{
return false;
}
if (value is Int16 || value is Int32 || value is Int64 || value is Decimal || value is Single || value is Double || value is Boolean)
{
return true;
}
try
{
if (value is string)
Double.Parse(value as string);
else
Double.Parse(value.ToString());
return true;
}
catch { }
return false;
}
It works for other data types. Should work fine for what you want to do.
if (int.TryParse(txtDepartmentNo.Text, out checkNumber) == false)
{
lblMessage.Text = string.Empty;
lblMessage.Visible = true;
lblMessage.ForeColor = Color.Maroon;
lblMessage.Text = "You have not entered a number";
return;
}
Here's a solution that allows either numeric only with a minus sign or decimal with a minus sign and decimal point. Most of the previous answers did not take into account selected text. If you change your textbox's ShortcutsEnabled to false, then you can't paste garbage into your textbox either (it disables right-clicking). Some solutions allowed you to enter data before the minus. Please verify that I've caught everything!
private bool DecimalOnly_KeyPress(TextBox txt, bool numeric, KeyPressEventArgs e)
{
if (numeric)
{
// Test first character - either text is blank or the selection starts at first character.
if (txt.Text == "" || txt.SelectionStart == 0)
{
// If the first character is a minus or digit, AND
// if the text does not contain a minus OR the selected text DOES contain a minus.
if ((e.KeyChar == '-' || char.IsDigit(e.KeyChar)) && (!txt.Text.Contains("-") || txt.SelectedText.Contains("-")))
return false;
else
return true;
}
else
{
// If it's not the first character, then it must be a digit or backspace
if (char.IsDigit(e.KeyChar) || e.KeyChar == Convert.ToChar(Keys.Back))
return false;
else
return true;
}
}
else
{
// Test first character - either text is blank or the selection starts at first character.
if (txt.Text == "" || txt.SelectionStart == 0)
{
// If the first character is a minus or digit, AND
// if the text does not contain a minus OR the selected text DOES contain a minus.
if ((e.KeyChar == '-' || char.IsDigit(e.KeyChar)) && (!txt.Text.Contains("-") || txt.SelectedText.Contains("-")))
return false;
else
{
// If the first character is a decimal point or digit, AND
// if the text does not contain a decimal point OR the selected text DOES contain a decimal point.
if ((e.KeyChar == '.' || char.IsDigit(e.KeyChar)) && (!txt.Text.Contains(".") || txt.SelectedText.Contains(".")))
return false;
else
return true;
}
}
else
{
// If it's not the first character, then it must be a digit or backspace OR
// a decimal point AND
// if the text does not contain a decimal point or the selected text does contain a decimal point.
if (char.IsDigit(e.KeyChar) || e.KeyChar == Convert.ToChar(Keys.Back) || (e.KeyChar == '.' && (!txt.Text.Contains(".") || txt.SelectedText.Contains("."))))
return false;
else
return true;
}
}
}
To check if the value is a double:
private void button1_Click(object sender, EventArgs e)
{
if (!double.TryParse(textBox1.Text, out var x))
{
System.Console.WriteLine("it's not a double ");
return;
}
System.Console.WriteLine("it's a double ");
}
I know this is an old question but I figured out I should pitch my answer anyways.
The following snippet iterates through each character of the text and uses the IsNumber() method, which returns true if the character is a number and false the other way, to check if all the characters are numbers. If all are numbers, the method returns true. If not it returns false.
using System;
private bool ValidateText(string text){
char[] characters = text.ToCharArray();
foreach(char c in characters){
if(!char.IsNumber(c))
return false;
}
return true;
}
Use Regex as below.
if (txtNumeric.Text.Length < 0 || !System.Text.RegularExpressions.Regex.IsMatch(txtNumeric.Text, "^[0-9]*$")) {
MessageBox.show("add content");
} else {
MessageBox.show("add content");
}