Monthly Archives: August 2009

Dutch bank account number check

For a Dutch customer I currently work for, I worked out the bank account number check (in Dutch: elfproef voor bankrekeningnummers). After checking out the Internet for the correct definition of Dutch bank account numbers (found on Wikipedia), I created the next check in C#:

var cleanAccNumber = accountNumber.Replace(".", "");

// A bank account number consists of 9 or 10 digits
if (!(cleanAccNumber.Length == 9 || cleanAccNumber.Length == 10)) return false;

// ... all being numeric and not resulting in a 0 when converted to a number ...
long l;
if (!long.TryParse(cleanAccNumber, out l)) return false;
if (l == 0) return false;

// pad it to the left to 10 digits with preceding zero's.
cleanAccNumber = cleanAccNumber.PadLeft(10, '0');

// ... the number must be validatable to the so-called 11-proof ...
long total = 0;
for (var i = 1; i <= cleanAccNumber.Length; i++)
// 11-proof for 10 digit bank account numbers (bron: Wikipedia): (1*A + 2*B + 3*C + 4*D + 5*E + 6*F + 7*G + 8*H + 9*H + 10*I) % 11 == 0
var number = Convert.ToInt32(cleanAccNumber[i - 1].ToString());
total += number*i;

// ... not result in a 0 when dividing by 11 ...
if (total == 0) return false;

// ... and not have a modulo when dividing by 11.
return total % 11 == 0;

Good luck when you should build one for yourself!

How to insert blank rule (<br />) from C# code

Once in a while I have to develop custom user controls that require blank rules in them. Almost always I think again: ‘I should have blogged about it, would have saved me lots of time searching’ :) … Well, no more, because here it is…

Many people using blank rules in C# code, use the following commands:

var brControl1 = new HtmlGenericControl { InnerHtml = "<br />" };
var brControl2 = new HtmlGenericControl("br");

However, brControl1 also prints a <span> tag and brControl2 prints <br></br>. Both options are not really useful. You should take notice of the fact that the HtmlGenericControl is not meant to be used for anything else than span, body, div and font (what is designed for ‘as the word goes’).  The way to go when printing a blank rule is:

var brControl3 = new LiteralControl("<br />");

This actually prints exactly what you would like it to print, namely <br />. Hope this helps you too :) ! BTW, if you are using the HtmlTextWriter class, you can also use the WriteBreak() function if you like.