Question

I have used the following code but it is returning false though it should return true

string check,zipcode;
zipcode="10001 New York, NY";
check=isalphanumeric(zipcode)

public static Boolean isAlphaNumeric(string strToCheck)
{
    Regex rg = new Regex("[^a-zA-Z0-9]");

    //if has non AlpahNumeric char, return false, else return true.
    return rg.IsMatch(strToCheck) == true ? false : true;
}

Answer 1

Try this one:

public static Boolean isAlphaNumeric(string strToCheck)
{
    Regex rg = new Regex(@"^[a-zA-Z0-9\s,]*$");
    return rg.IsMatch(strToCheck);
}

It’s more undestandable, if you specify in regex, what your string SHOULD contain, and not what it MUST NOT.

In the example above:

• ^ – means start of the string
• []* – could contain any number of characters between brackets
• a-zA-Z0-9 – any alphanumeric characters
• \s – any space characters (space/tab/etc.)
• , – commas
• $ – end of the string