parsing - What are these odd errors that occur when I attempt to generate C# with ANTLR4? -

i'm (now) trying use antlr4 , c# design language, , far i've been fiddling around it. in process, decided try , create simple mathematical expression evaluator. in process, created following antlr grammar it:

grammar calculator;  @parser::members {     protected const int eof = eof; }  @lexer::members {     protected const int eof = eof;     protected const int hidden = hidden; }  program : expr+ ;  expr : expr op=('*' | '/') expr      | expr op=('+' | '-') expr      | int      | '(' expression ')'      ;  int : [0-9]+ ; mul : '*' ; div : '/' ; add : '+' ; sub : '-' ; ws : (' ' | '\r' | '\n') -> channel(hidden) ; 

when try generate c# code using command:

java -jar c:\...\antlr-4.2-complete.jar -dlanguage=csharp .\...\grammar.g4 

i these odd errors:

error(50): c:\users\ethan\documents\visual studio 2015\projects\cypresslang\cypresslang\source\.\grammar\cypressgrammar.g4:1:0: syntax error: 'ï' came complete surprise me     error(50): c:\users\ethan\documents\visual studio 2015\projects\cypresslang\cypresslang\source\.\grammar\cypressgrammar.g4:1:1: syntax error: '»' came complete surprise me     error(50): c:\users\ethan\documents\visual studio 2015\projects\cypresslang\cypresslang\source\.\grammar\cypressgrammar.g4:1:2: syntax error: '¿' came complete surprise me   error(50): c:\users\ethan\documents\visual studio 2015\projects\cypresslang\cypresslang\source\.\grammar\cypressgrammar.g4:1:3: syntax error: mismatched input 'grammar' expecting semi 

what might causing these errors, , how can fix them? best guess @ moment visual studio inserting odd characters onto beginning of file, , can't remove them.

today not day.

visual studio decided mess me , change file formats utf-8 of files. needed go file > advanced save settings, , change encoding us-ascii. removed odd characters inserted @ beginning, , solved (most) of problems.