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

Question

I'm (now) trying to use ANTLR4 and C# to design a language, and so far I've been fiddling around with it. In the process, I decided to try and create a simple mathematical expression evaluator. In the process, I created the following ANTLR grammar for 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 I try to generate C# code from it using this command:

java -jar C:\...\antlr-4.2-complete.jar -DLanguage=CSharp .\...\Grammar.g4

I get 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 as a complete surprise to me    
error(50): C:\Users\Ethan\Documents\Visual Studio 2015\Projects\CypressLang\CypressLang\Source\.\Grammar\CypressGrammar.g4:1:1: syntax error: '»' came as a complete surprise to me    
error(50): C:\Users\Ethan\Documents\Visual Studio 2015\Projects\CypressLang\CypressLang\Source\.\Grammar\CypressGrammar.g4:1:2: syntax error: '¿' came as a complete surprise to 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 be causing these errors, and how can I fix them? My best guess at the moment is that Visual Studio is inserting odd characters onto the beginning of the file, and I can't remove them.

Buchanan

Answer 1

Today is not a good day.

Visual Studio decided to mess with me and change my file formats to UTF-8 for all of my files. All I needed to do was go to File > Advanced Save Settings, and change the encoding to US-ASCII. This removed the odd characters inserted at the beginning, and solved (most) of my problems.

Buchanan

These "odd" characters is the socalled BOM (byte order mark). The file has been stored in UTF-8 probably where the BOM consists of 3 bytes (those you got the warning for). You can store a Unicode file with or w/o BOM and don't have to return to ASCII encoding, just to get rid of the BOM. – Newsletter

@Ethan...Thank the Lord I find your answer. Save me hours of digging – Angara