[Beginner Question]A question about yacc & lex

["Wen Yi" <896634148@xxxxxx>]

Hi team,

now I'm learning the yacc & lex to understand the principle of the postgres's parser.

And I write a test program as this:

/*
    array.l
        Array program
    Wen Yi
*/
%option noyywrap
%option noinput

%{
#include <stdlib.h>
#include "y.tab.h"
%}

%%

[0-9]+ { yylval.number = atoi(yytext); return NUMBER;}

\n { return END; }

%%

/*
    array.y
        Array program
    Wen Yi
*/

%{
#include <stdio.h>
int yylex();
int yyerror(char *s);
%}
%token NUMBER
%token END
%union
{
    int number;
}

%%

end:
| array_list END { printf ("= %d\n", $1.number); }

array_list: array { $$.number = $1.number; }

array: number { $$.number = $1.number; }
| array number { $$.number = $1.number + $2.number; }

number: NUMBER { $$.number = $1.number;  }

%%

int main(int argc, char *argv[])
{
    yyparse();
}
int yyerror(char *s)
{
    puts(s);
}

The running result is this:

[beginnerc@bogon code]$ ./a.out
1 2 3 4 5 6
     = 21
1
syntax error

I don't know  why are there many extra spaces in the output, and why the error message 'syntax error' is showed.

Can someone give me some advice?

Thanks in advance!

Yours,

Wen Yi