Best way to get the first digit from an integer of varying length in VB.NET

Question

I am a newbie to programming and need some help with the basics.

I have a function which takes in an integer value. I want to be able to grab the first digit (or the first and second digits in some cases) of this integer and do something with it.

What is the best way in VB.NET to get the first digit of an integer (or the first and second)?

Answer 1

If you need the digits starting from the end of the integer, just get the modulu result for the tens or the hundreds, according to how many digits you need.

Dim n As Integer
n Mod 10

for the first digit, or:

n Mod 100

for the second and first digits.

If you need the first and second digits from the beginning of the number, there is another answer here which will probably help you.

Answer 2

I'm not well versed in VB syntax, so forgive me for the syntax errors:

dim i as integer
while i >= 10
    i = i \ 10
end while
msgbox "i = " & i

Note, this prints the "first from the left" digit. Like, for "12345" it would print "1".

Answer 3

Hi there.

To Yuval, are you sure your answer is correct? I just tried this:

Module Module1

    Sub Main()
        Dim i As Integer = 34

        Dim k As Integer = i Mod 10

    End Sub

End Module

and the result of k is 4, not 3. The Mod operator rounded up the number.

Answer 4

firstDigit = number.ToString().Substring(0,1)

firstTwoDigits = number.ToString().Substring(0,2);

int.Parse(firstDigit)

int.Parse(firstTwoDigits)

and so forth

Answer 5

for first digit you can use:

  Dim number As Integer = 234734
  Dim first = number.ToString.ToCharArray()(0)

for second digit you can use:

 Dim number As Integer = 234734
 Dim second = number.ToString.ToCharArray()(1)

Answer 6

This would work. You can use Math.ABS, absolute value, to eliminate negative. The number from left could be replaced by a function if you are using logic, like the overall length of the number, to determine how many of the leading characters you are going to use.

Dim number As Integer = -107
Dim result As String
Dim numberFromLeft As Integer = 2

result = Math.Abs(number).ToString.Substring(0, numberFromLeft)

This results in 10 it is a string but converting it back to a number is easy if you need to. If you need to keep track if it was positive or negative you could use the original value to apply that back to you parsed string.