ip 号码前导零

Question

I am trying to know if an IP address is valid, but I want my method to return false if any of the 4 IP components has a leading zero, and is not 000 or 0 .

I've tried to do it in one instruction:

public static bool is_valid_IP(String ip) {
 try {
  return ip.Split('.')
         .ToList()
         .Where(x => Convert.ToInt32(x)<=255 && Convert.ToInt32(x)>=0  && notleadingzerocontition)
         .Count()==4;
  } catch(Exception) {
          return false;
  }
 }

What I need is that not leading zero condition goes true if its 000, but otherwise if the IP number contains any leading zero it goes false.

For example:

• 0 -> true
• 000 -> true
• 01 -> false
• 001 -> false
• 20 -> true

There are better solutions using regex patterns, but I'm practising LINQ.

Can I do this in one statement using LINQ?

Answer 1

Here is one way to do it. Weird Where clause reflects the weirdness of the requirements.

public static bool is_valid_IP(String ip)
{
    var parts = ip.Split('.');

    return parts.Length == 4 && parts
        .Select(x => new { StringValue = x, Parsed = int.TryParse(x, out int i), IntValue = i })
        .Where(x => x.Parsed && x.IntValue <= 255 && x.IntValue >= 0 &&
            (x.StringValue[0] != '0' || x.StringValue == "0" || x.StringValue == "000"))
        .Count() == 4;
}