convert from decimal(base-10) to alphanumeric(base-36)

Question

_{Monday, May 22, 2006 3:46 AM | 1 vote}

dear All,

I am creating a program that generate id for any incoming material lot using hexadecimal ID, Since the number of incoming material lot increasing rapidly, we plan to move to a new ID number with alphanumeric(0-9,A-Z).

The convert class doesn't support the base 36 type. Does anyone have any idea for my problem? Any help is very appreciated.

Thank you

regards

Freddy Halim

All replies (9)

_{Monday, May 22, 2006 6:41 AM ✅Answered | 3 votes}

Hi,
check if works for you:

public String ConvertToBase(int num, int nbase)
{
    String chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    // check if we can convert to another base
    if(nbase < 2 || nbase > chars.Length)
        return "";

    int r;
    String newNumber = "";

    // in r we have the offset of the char that was converted to the new base
    while(num >= nbase)
    {
        r = num % nbase;
        newNumber = chars[r] + newNumber;
        num = num / nbase;
    }
    // the last number to convert
    newNumber = chars[num] + newNumber;

    return newNumber;
}

_{Monday, May 22, 2006 7:42 AM}

Dear  n0n4me,

Yeah its works. Looking at your code, i think i can start create the opposite conversion from base36 to base10 too.

Thank you for your help. Your help is very appreciated and invaluable for me.

Warmest Regards,

Freddy Halim

_{Monday, May 22, 2006 11:35 AM}

Glad it helped.
If you need any help converting from base 36 -> base 10 just ask. But it shouldn't be difficult. :)

_{Wednesday, September 13, 2006 10:08 PM}

n0n4m3,

I was hoping that you could help me by posting the code to convert from base-36 to base-10

Thanks in advance,

MMcNamara

_{Thursday, September 14, 2006 3:10 PM}

Actually, you may want to use the standard Base-40 encoding (which is supported by .Net)

for(long i = 100000; i < 200000; ++i)
{
    string enc = Convert.ToBase64String(BitConverter.GetBytes(i));
    long dec = BitConverter.ToInt64(Convert.FromBase64String(enc), 0);
    Console.WriteLine("From {0}, to {1}, to {2}", i, enc, dec);
}

_{Tuesday, June 11, 2013 5:06 PM}

I needed this logic in VB, so here is your code written in Visual Basic. 

(Could not find a similar forum for VB)

    ' Convert Base10 to any other Base (2 to 36)
    ' From msdn.microsoft.com forum C# code - converted to VB

    Public Function convertToBase(ByVal value As Int32, base As Int32) As String

        Dim chars As String = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        Dim r As Int32
        Dim newNumber As String

        If (base < 2 Or base > chars.Length) Then
            Return ""
        End If

        newNumber = ""

        While value >= base
            r = value Mod base
            newNumber = chars.Substring(r, 1) & newNumber
            value = Convert.ItInt32(Math.Floor(value / base))     ' Don't want to round up
        End While
        If value > 0 Then
            newNumber = chars.Substring(value, 1) & newNumber
        End If

        If String.IsNullOrEmpty(newNumber) Then
            newNumber = "0"
        End If

        r = Nothing
        chars = Nothing

        Return newNumber

    End Function

_{Thursday, June 13, 2013 7:29 PM}

That would be the aptly named Visual Basic forum.

Karl

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_{Thursday, January 15, 2015 6:28 AM | 2 votes}

You can succinctly perform this task with Linq and avoid having an alphabet constant at all as well as support converting from any base (2 to 36) to base 10 as follows:

    string b36 = "000A", tbase = 36;
    int b10 = b36
           .Select(d => d >= '0' && d <= '9' ? d - '0' : 10 + char.ToUpper(d) - 'A')
           .Aggregate(0, (pos, d) => pos * tbase + d);

For completeness (to go from base 10 to any base):

    int value = 10, tbase = 36;
    string result = "";
    while (value > 0)
    {
        int x = value % tbase;
        result = (char)(x >= 0 && x <= 9 ? x + 48 : x + 'A' - 10) + result;
        value /= tbase;
    }
    Console.WriteLine(result.PadLeft(4,'0'));

_{Thursday, December 3, 2015 8:03 PM}

    // check if we can convert to another base
    if(nbase < 2 || nbase > chars.Length)
        return "";

This bounds check should throw an ArgumentOutOfRange exception rather than just returning an empty string.  In .NET, if a function can't accomplish what it is supposed to do then it should throw.

Regards, David Totzke