Title: Check Valid IP Address
Question: A simple way to check whether an IP address is valid.
Answer:
function IsIPAddress(zvIPAddressID: string): boolean;
var
ipLengthOfGroup, ipPosition, ipNoOfGroups: integer;
ipGroupNum, Code: integer;
begin
IsIpAddress := False;
ipNoOfGroups := 0;
ipLengthOfGroup := 0;
for ipPosition := 1 to Length(zvIPAddressID) do
case Ord(zvIPAddressID[ipPosition]) of
48..57:
begin
inc(ipLengthOfGroup);
if (ipLengthOfGroup 3) then exit;
end;
46:
begin
inc(ipNoOfGroups);
Val(Copy(zvIPAddressID, ipPosition - ipLengthOfGroup, ipLengthOfGroup), ipGroupNum, Code);
if ((ipNoOfGroups 3) or (ipLengthOfGroup = 0)) or (ipGroupNum 255) then exit;
ipLengthOfGroup := 0;
end;
else
exit;
end;
Val(Copy(zvIPAddressID, ipPosition - ipLengthOfGroup, ipLengthOfGroup), ipGroupNum, Code);
IsIPAddress := (ipNoOfGroups = 3) and (ipLengthOfGroup 0) and (ipGroupNum end;