How to I condition a text box for a string if it holds a integer

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I'm currently having some issues with error checking on a textbox. It holds a variable (called Price) as Double. Its purpose is to take a number in, and when a button is clicked it adds it to a running total displayed in a different textbox.

Now I have an error when checking if the textbox is empty using:

!string.IsNullOrWhiteSpace(txtAddItem.Text)

However, I'm unsure of how to error check if a string or character other than a number has been entered. Any ideas are appreciated.


Method 1: RegEx

You should try to use a regular expression. Regular expressions (Regex in short) are used to match strings against patterns. For example, if you only want to allow integers:

Regex r = new Regex(@"^[0-9]+$")

The Regex class has an .IsMatch(string s) method, where s is the string you want to test against the pattern.

Method 2: try-catch and Parse()

Another way to do it, which might be a bit more beginner-friendly, is a try-catch block. (I am assuming your TextBox's name is TextBox1 and you store the sum value in a runningSum variable.)

try {
    double x = double.Parse(TextBox1.Text);
    runningSum += x;
catch (ArgumentException ax) {
    //handle if it is not a number in the TextBox
}

Method 3: TryParse()

A more advanced version which combines try-catch and Parse() is using the double.TryParse() method which returns a true/false value based on whether conversion was successful or not.

double x;
if (double.TryParse(TextBox1.Text, out x)) {
    runningSum += x;
} else {
    //handle if it is not a number in the TextBox.
}

[Solved] get only integer value in text box, you need regex for this. Hide Copy Code. //first you need to include header file using System.Text.RegularExpressions; string newString� try { double x = double.Parse(TextBox1.Text); runningSum += x; catch (ArgumentException ax) { //handle if it is not a number in the TextBox } Method 3: TryParse() A more advanced version which combines try-catch and Parse() is using the double.TryParse() method which returns a true/false value based on whether conversion was successful or not.


If the value needs to be a valid double you could use 'double.TryParse'. Something like:

if (double.TryParse(txtAddItem.Text, out double price) == false)
{
  // Show error or clear textbox
}
else
{
  // Value is valid, add to total
}

How do I make a textbox that only accepts numbers ? C#, VB.Net , Validating a textbox to allow only numeric values , How to allow only numbers in a textbox A TextBox control is used to display, or accept as input, a single line of text. TextBox control has additional functionality that is not found in the standard a TextBox that automatically completes user input strings by comparing the� If i do the conditional expressions it comes back with Incompatible conditional operand types Number and int value = (java.lang.String). So if I turn the AptCount to a String, it kind of defeats the purpose of adding them and totaling them. At a loss right now.


You can use Double.TryParse()

double number;
if (Double.TryParse(txtAddItem.Text, out number)) {
    Console.WriteLine("'{0}' is a valid double: {1}", value, number);
} else {
    Console.WriteLine("Unable to parse '{0}' as a valid double", value);
} 

TextBox Control, A TextBox control is used to display, or accept as input, a single line of text. Keydown event occurs when a key is pressed while the control has focus. Parse method Converts the string representation of a number to its integer Many of us have faced a situation where we want the user to enter a number in a TextBox. The display width of the text box, in characters, is determined by its Columns property. If the TextBox control is a multiline text box, the number of rows it displays is determined by the Rows property. To display text that wraps within the TextBox control, set the Wrap property to true.


JavaScript : Checking for all numbers, Javascript function to check if a field in a html form contains all numbers or not. Sometimes situations arise (input a phone number, zip code or credit card number) To get a string contains only numbers (0-9) we use a regular <meta charset="utf-8"> <title>JavaScript form validation - An integer with an� Rename it to ‘GetNumber’ Add another string parameter (RegexPattern) that will accept the Regex pattern string. Add a line that removes ‘-‘ characters from the string. This is more important for the decimal pattern than it was for the integer pattern as the decimal pattern forces a search from the start of the string.


is_int - Manual, (current page); /: Focus search box. is_integer � is_int — Find whether the type of a variable is integer Note: To test if a variable is a number or a numeric string (such as form input, which is always a string), you must use is_numeric(). This will check if something has an acceptable integer value, such as a string with int� In this case your Textbox accept only numbers. The following method also you can force your user to enter numeric value only. if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar)){ e.Handled = true;} If you want to allow decimals add the following to the above code.


visual c# .net - getting numbers from text boxes, What we'll do is show you how to get numbers from text boxes, and then use set up another integer variable to hold the second number from the new text box:. Python input() function always convert the user input into a string. but how to check user input is a number. We can Convert string input to int or float type to check string input is an integer type. also using isdigit() method of string class we can check input string is number or string.