C#: recognize Operators as such, fix split-up numeric literals

Fixes #2256

CHANGES

@@ -23,6 +23,7 @@ Version 2.14.0
   * C family (C, C++ and many others): fix an issue where a chunk would
     be wrongly recognized as a function definition due to braces in
     comments (#2210)
+  * C#: fix number and operator recognition (#2257)
   * gas (GNU assembler): recognize braces as punctuation (#2230)
   * HTTP: add `CONNECT` keyword
   * Inform 6: fix lexing of properties and doubles (#2214)

pygments/lexers/dotnet.py

@@ -85,12 +85,19 @@ class CSharpLexer(RegexLexer):
                 (r'//.*?\n', Comment.Single),
                 (r'/[*].*?[*]/', Comment.Multiline),
                 (r'\n', Whitespace),
-                (r'[~!%^&*()+=|\[\]:;,.<>/?-]', Punctuation),
+                (words((
+                    '>>>=', '>>=', '<<=', '<=', '>=', '+=', '-=', '*=', '/=',
+                    '%=', '&=', '|=', '^=', '??=', '=>', '??', '?.', '!=', '==',
+                    '&&', '||', '>>>', '>>', '<<', '++', '--', '+', '-', '*',
+                    '/', '%', '&', '|', '^', '<', '>', '?', '!', '~', '=',
+                )), Operator),
+                (r'=~|!=|==|<<|>>|[-+/*%=<>&^|]', Operator),
+                (r'[()\[\];:,.]', Punctuation),
                 (r'[{}]', Punctuation),
                 (r'@"(""|[^"])*"', String),
                 (r'\$?"(\\\\|\\[^\\]|[^"\\\n])*["\n]', String),
                 (r"'\\.'|'[^\\]'", String.Char),
-                (r"[0-9](\.[0-9]*)?([eE][+-][0-9]+)?"
+                (r"[0-9]+(\.[0-9]*)?([eE][+-][0-9]+)?"
                  r"[flFLdD]?|0[xX][0-9a-fA-F]+[Ll]?", Number),
                 (r'(#)([ \t]*)(if|endif|else|elif|define|undef|'
                  r'line|error|warning|region|endregion|pragma)\b(.*?)(\n)',