Optimize string concatenation in network utility methods (#3225)

* Initial plan

* Optimize string concatenation in network utilities

Co-authored-by: BornToBeRoot <[email protected]>

* Complete performance optimization

Co-authored-by: BornToBeRoot <[email protected]>

* Remove accidentally committed binary file

Co-authored-by: BornToBeRoot <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: BornToBeRoot <[email protected]>

Author: Copilot

.nuget/.gitignore

@@ -0,0 +1 @@
+*.exe

Source/NETworkManager.Models/Network/IPv4Address.cs

@@ -100,17 +100,7 @@ public static bool IsMulticast(IPAddress ipAddress)
     /// <returns>IP addresses as string.</returns>
     public static object ConvertIPAddressListToString(IEnumerable<IPAddress> ipAddresses, string delimiter = null)
     {
-        var result = string.Empty;
-
-        foreach (var ipAddr in ipAddresses)
-        {
-            if (!string.IsNullOrEmpty(result))
-                result += delimiter ?? Environment.NewLine;
-
-            result += ipAddr.ToString();
-        }
-
-        return result;
+        return string.Join(delimiter ?? Environment.NewLine, ipAddresses);
     }
 
     /// <summary>
@@ -121,16 +111,7 @@ public static object ConvertIPAddressListToString(IEnumerable<IPAddress> ipAddre
     public static object ConvertIPAddressWithSubnetmaskListToString(Tuple<IPAddress, IPAddress>[] ipAddresses,
         string delimiter = null)
     {
-        var result = string.Empty;
-
-        foreach (var ipAddr in ipAddresses)
-        {
-            if (!string.IsNullOrEmpty(result))
-                result += delimiter ?? Environment.NewLine;
-
-            result += ipAddr.Item1 + "/" + Subnetmask.ConvertSubnetmaskToCidr(ipAddr.Item2);
-        }
-
-        return result;
+        return string.Join(delimiter ?? Environment.NewLine,
+            ipAddresses.Select(ipAddr => $"{ipAddr.Item1}/{Subnetmask.ConvertSubnetmaskToCidr(ipAddr.Item2)}"));
     }
 }

Source/NETworkManager.Models/Network/Subnetmask.cs

@@ -28,10 +28,7 @@ public static SubnetmaskInfo GetFromCidr(int cidr)
 
     public static string ConvertCidrToSubnetmask(int cidr)
     {
-        var bits = string.Empty;
-
-        for (var i = 0; i < cidr; i++)
-            bits += "1";
+        var bits = new string('1', cidr);
 
         return IPv4Address.ToHumanString(bits.PadRight(32, '0'));
     }