CODEWITHSUNDEEP
vb.net
user3439015
user3439015

Reputation: 25

How to Error handling in VB

How can I make a Exception handling piece of code for to ensure numeric entry? I am doing my final for my visual basic class and there are some errors I would like to make my program perfect :). Sorry for the title they are really hard to make. I want it so the program doesnt close when someone types a string instead of a integer.

Module Module1

Sub Main()
    Dim year, age, again As Integer
retry:
    Console.WriteLine("Enter The year you were born in!")
    Console.WriteLine("")
    year = Console.ReadLine()
    Console.WriteLine("")
    If year < 1894 Or year > 2014 Then GoTo Toyoung

    age = 2014 - year
    Console.WriteLine("You are " & age & " years old")
    Console.WriteLine("")

Upvotes: 1

Views: 300

Answers (2)

xpda
xpda

Reputation: 15813

One way is to input a string, and check to make sure it's numeric with isnumeric, like this:

Sub Main()
    Dim year, age, again As Integer
    Dim s as string
retry:
    Console.WriteLine("Enter The year you were born in!")
    Console.WriteLine("")
    s = Console.ReadLine()
    Console.WriteLine("")
    if not isnumeric(s) then goto retry
    year = s
    If year < 1894 Or year > 2014 Then GoTo Toyoung

    age = 2014 - year
    Console.WriteLine("You are " & age & " years old")
    Console.WriteLine("")

An alternative method is to use a Try, Catch block. It is preferred by some people.

Upvotes: 1

logixologist
logixologist

Reputation: 3834

Normally exception handling in VB.NET works this way.

With the start of each process you do this

TRY
''Put some code here

CATCH
''Put code on what to do if it throws an error

FINALLY
''Optional: Any thing that has to be done regardless of wether it throws 
''an exception or not. Usually here is where you would close the connection

END TRY

In your case you just need to Validate the user input. What you will need to do is to check to see if isnumber(nameoftextbox) = False then give the user a message and exit the subroutine.

Upvotes: 3

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