UK Postcode Validation

Regular expression for JavaScript

var regPostcode = /^([a-zA-Z]){1}([0-9][0-9]|[0-9]|[a-zA-Z][0-9][a-zA-Z]|[a-zA-Z][0-9][0-9]|[a-zA-Z][0-9]){1}([ ])([0-9][a-zA-z][a-zA-z]){1}$/;

var result = regPostcode.test(SearchTerm);

if (!result) {
alert(“Please enter valid postcode”);
return false;
}

Regular expression for C#

string regPostcode = “([a-zA-Z]){1}([0-9][0-9]|[0-9]|[a-zA-Z][0-9][a-zA-Z]|[a-zA-Z][0-9][0-9]|[a-zA-Z][0-9]){1}([ ])([0-9][a-zA-z][a-zA-z]){1}”;

System.Text.RegularExpressions.Regex regx = new System.Text.RegularExpressions.Regex(regPostcode);

if(!regx.IsMatch(address0.PostalCode))
{
results.Add(new ValidationResult(String.Format(“Please enter valid postcode for {0}.”, addressRank)));
}

You can check the regular expression at http://www.regexplanet.com/

Postal code format and sample postcodes are as below.