Use code page numbers

Author: Shane32

QRCoder/QRCodeGenerator.cs

@@ -745,7 +745,7 @@ bool IsUtf8()
             }
         }
 
-        private static readonly Encoding _iso88591ExceptionFallback = Encoding.GetEncoding("ISO-8859-1", new EncoderExceptionFallback(), new DecoderExceptionFallback());
+        private static readonly Encoding _iso88591ExceptionFallback = Encoding.GetEncoding(28591, new EncoderExceptionFallback(), new DecoderExceptionFallback()); // ISO-8859-1
         /// <summary>
         /// Checks if the given string can be accurately represented and retrieved in ISO-8859-1 encoding.
         /// </summary>
@@ -877,7 +877,7 @@ private static BitArray PlainTextToBinaryAlphanumeric(string plainText)
 #if NET5_0_OR_GREATER
             Encoding.Latin1;
 #else
-            Encoding.GetEncoding("ISO-8859-1");
+            Encoding.GetEncoding(28591); // ISO-8859-1
 #endif
         private static Encoding _iso8859_2;
 
@@ -920,7 +920,7 @@ private static BitArray PlainTextToBinaryByte(string plainText, EciMode eciMode,
                         // Users must install the System.Text.Encoding.CodePages package and call Encoding.RegisterProvider(CodePagesEncodingProvider.Instance)
                         // before using this encoding mode.
                         if (_iso8859_2 == null)
-                            _iso8859_2 = Encoding.GetEncoding("ISO-8859-2");
+                            _iso8859_2 = Encoding.GetEncoding(28592); // ISO-8859-2
                         // Convert text to ISO-8859-2 and encode.
                         targetEncoding = _iso8859_2;
                         utf8BOM = false;

QRCoderTests/QRGeneratorTests.cs

@@ -195,7 +195,9 @@ public void can_generate_from_bytes()
         [Category("QRGenerator/TextEncoding")]
         public void isValidIso_works()
         {
-            Encoding _iso88591ExceptionFallback = Encoding.GetEncoding("ISO-8859-1", new EncoderExceptionFallback(), new DecoderExceptionFallback());
+            // see private method: QRCodeGenerator.IsValidISO
+
+            Encoding _iso88591ExceptionFallback = Encoding.GetEncoding(28591, new EncoderExceptionFallback(), new DecoderExceptionFallback()); // ISO-8859-1
 
             IsValidISO("abc").ShouldBeTrue();
             IsValidISO("äöü").ShouldBeTrue();