CODEWITHSUNDEEP
c++flex-lexer
Madeline
Madeline

Reputation: 645

'Pre-mature EOF' and 'Bad Character' errors

I have written Flex stuff in a previous class but none of my previously working code is solving the issue I am having.

I have searched around StackOverflow for a solution but none of them have solved it.

I have:

Here is my code (I removed all the tokens and such because there is a lot of them):

%{

...

int numLines = 0;

void printTokenInfo(char* tokenType, char* lexeme);

void handleComments(char* text);

%}

WSPACE  [ \t\r]+
NEWLINE \n
DIGIT [0-9]
LETTER [a-zA-Z]
IDENT ({LETTER}|_)({LETTER}|{DIGIT}|_)* 
INTCONST {DIGIT}+
CHARCONST "'"{LETTER}+"'"

%%

... 

%%

// User-written code goes here
void printTokenInfo(char* tokenType, char* lexeme) 
{
    printf("A");
    printf("TOKEN: %s LEXEME: %s\n", tokenType, lexeme);
}

void handleComments(char* text) 
{
    printf("%s\n", text);
}

int yywrap() { return 1; }

int main() 
{
    do {
        yylex();
    } while (!feof(yyin));
    return 0;
}

Here is how I am compiling and running it:

flex FILENAME.l
g++ lex.yy.c -o lexer
lexer < INPUT.txt

And the instructor provided us with input files but none of them have worked. They all fail with 'premature EOF' or 'bad character'

Any ideas?

Upvotes: 0

Views: 389

Answers (1)

Madeline
Madeline

Reputation: 645

Well, I think I finally discovered the answer... Try running it with the complete path rather than just the name of your compiled lexer. I discovered the 'actual' path by running it under gdb (Which admittedly should have been my first instinct). 

gdb lexer
(gdb) run < INPUT.txt

Originally, I was trying to run it with:

lexer < INPUT.txt

But I discovered by running it with gdb that this worked:

/nethome/users/mjc7w6/Classes/lexer < INPUT.txt

Edit: Someone chimed in on my Facebook with a further improvement. If the above solution fixes it for you, you might need to edit your ~/.bashrc with the following:

export PATH=/nethome/users/mjc7w6/Classes:$PATH

Or however you find that path to be set-up.

Upvotes: 2

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