String in Visual Basic .NET

In Visual Basic .NET, you can use the IsNumeric() function to check if a string is a number or not.

Here's an example code snippet to check if a string is a number:

Dim userInput As String = "12345"
If IsNumeric(userInput) Then
    Console.WriteLine("The input is a number.")
Else
    Console.WriteLine("The input is not a number.")
End If

In the code snippet above, we define a string variable called userInput and assign it the value "12345". We then use the IsNumeric() function to check if the value of userInput is numeric or not. If the input is numeric, the program will output "The input is a number." to the console. If it is not, the program will output "The input is not a number."

Here's another example that shows what happens when the input is not a number:

Dim userInput As String = "hello"
If IsNumeric(userInput) Then
    Console.WriteLine("The input is a number.")
Else
    Console.WriteLine("The input is not a number.")
End If

In this example, we set the value of userInput to "hello", which is not a number. When we run the program, it will output "The input is not a number." to the console.

Note that the IsNumeric() function will return True for numeric values represented as strings, such as "-123.45". However, it will also return True for other non-numeric values such as currency symbols, so it's important to use additional validation to ensure that the input is actually a valid number.