is numeric
Post on 01-Jul-2015
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IS NUMERIC?Just one way we can protect the user
from themselves!
Sometimes You want the user to enter only numbers . . .
Module Module1
Sub Main()
Dim favouriteNumber As Integer
Console.WriteLine("What's your favourite number?")
favouriteNumber = Console.ReadLine()
Console.WriteLine("Your favourite number is " &
favouriteNumber)
Console.ReadLine()
End Sub
End Module
Sometimes You want the user to enter only numbers . . .
If I enter the number 5, the program works
Sometimes You want the user to enter only numbers . . .
If I enter five however, things start to break down
Sometimes You want the user to enter only numbers . . .
BUT THAT STILL MAKES
SENSE TO ME!!
Sometimes You want the user to enter only numbers . . .
Visual Studio is telling us there’s a InvalidCastException
Sometimes You want the user to enter only numbers . . .
Visual Studio is telling us there’s a InvalidCastException
Visual Studio is telling us that it can’t put the word fiveinto the variable favouriteNumber
Remember, Variables have a specific data type
ChampagneBucket
Variables have a data typeI’m the type of
Variable that holds only
Champagne ! Don’t you try
and put Lemonade in
me!
Example data types
ChampagneBucket
String IntegerDouble
Float Char
Boolean
You need to protect the user
from themselves . . .
You’re gonna need some isNumeric
validationprotection . . .
!
isNumeric
IsNumeric(temp)
We can use the isNumeric() function to tell if a number entered by the user is a number
The variable it will check is a number
isNumericisNumeric() will return either true or false depending
on the input it is given
Adding isNumericModule Module1
Sub Main()
Dim favouriteNumber As Integer
Console.WriteLine("What's your favourite number?")
Dim temp As String
temp = Console.ReadLine()
While Not IsNumeric(temp)
Console.WriteLine("YOU HAVEN'T ENTERED NUMBER!")
temp = Console.ReadLine()
End While
favouriteNumber = temp
Console.WriteLine("Your favourite number is " & favouriteNumber)
Console.ReadLine()
End Sub
End Module
Adding isNumeric
The user has been stopped from entering the word five
Thanks!
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