a yacc problem, help!

[betterking@gmail.com]

I want to write a tiny sql parser with lex and yacc. At first I just
write sql.l sql.y with simple CREATE TABLE funciton.

sql.l

%{
#include "y.tab.h" //<>
#include <stdlib.h>
#include <string.h>
void yyerror(char *);
%}

%%
CREATE { return CREATE;}

TABLE { return TABLE;}


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

[a-z][a-z0-9]* {
strcpy(yylval.n ameval,
yytext);
// fprintf(stderr,
"-----%s\n", *yytext);
return NAME;
}

[<>=] {
yylval.compval =
yytext[0];
return COMPARE;
}

[\n] { return *yytext;
}

[ \t] ;

.. {
yyerror("Unknow n
Character!");
}
%%

int yywrap(void)
{
return 1;
}


sql.y:

%{
#include <stdio.h>
void yyerror(char *s);
int yylex(void);

%}

%union {
int intval;
char nameval[50];
char compval;
};

%token <intvalINTEGE R
%token <namevalNAME
%token <compvalCOMPA RE
%token CREATE TABLE

%%
createtablestat ement:
| createtablestat ement '\n'
| CREATE TABLE NAME '\n' {printf("%s\n", $3);}
;

%%
void yyerror(char *s)
{
fprintf(stderr, " %s\n", s);
}

int main(void)
{
yyparse();
}


I compile and run it as follows:

lex sql.l
yacc -d sql.y
gcc -o create lex.yy.c y.tab.c -ll

$./create
CREATE TABLE aaaa
aaaa
CREATE TABLE bbbb
parse error
$

I want to know why it could run at the first time, but it could not
run at the second time.
Please help me. Thanks a lot!

[Nick Keighley]

Re: a yacc problem, help!

On 4 Oct, 03:10, "betterk...@gma il.com" <betterk...@gma il.comwrote:

I want to write a tiny sql parser with lex and yacc. At first I just
write sql.l sql.y with simple CREATE TABLE funciton.

<snip>

both yacc and sql are off-topic in comp.lang.c.
You need to try a compiler or unix ng for questions
about yacc.


--
Nick Keighley

[Dann Corbit]

Re: a yacc problem, help!

<betterking@gma il.comwrote in message
news:d4919413-2c09-49ae-b990-70bc75a7cd8a@x4 1g2000hsb.googl egroups.com...

>I want to write a tiny sql parser with lex and yacc. At first I just
write sql.l sql.y with simple CREATE TABLE funciton.
>
sql.l
>
%{
#include "y.tab.h" //<>
#include <stdlib.h>
#include <string.h>
void yyerror(char *);
%}
>
%%
CREATE { return CREATE;}
>
TABLE { return TABLE;}
>
>
[0-9]+ {
yylval.intval =
atoi(yytext);
return INTEGER;
}
>
[a-z][a-z0-9]* {
strcpy(yylval.n ameval,
yytext);
// fprintf(stderr,
"-----%s\n", *yytext);
return NAME;
}
>
[<>=] {
yylval.compval =
yytext[0];
return COMPARE;
}
>
[\n] { return *yytext;
}
>
[ \t] ;
>
. {
yyerror("Unknow n
Character!");
}
%%
>
int yywrap(void)
{
return 1;
}
>
>
sql.y:
>
%{
#include <stdio.h>
void yyerror(char *s);
int yylex(void);
>
%}
>
%union {
int intval;
char nameval[50];
char compval;
};
>
%token <intvalINTEGE R
%token <namevalNAME
%token <compvalCOMPA RE
%token CREATE TABLE
>
%%
createtablestat ement:
| createtablestat ement '\n'
| CREATE TABLE NAME '\n' {printf("%s\n", $3);}
;
>
%%
void yyerror(char *s)
{
fprintf(stderr, " %s\n", s);
}
>
int main(void)
{
yyparse();
}
>
>
I compile and run it as follows:
>
lex sql.l
yacc -d sql.y
gcc -o create lex.yy.c y.tab.c -ll
>
$./create
CREATE TABLE aaaa
aaaa
CREATE TABLE bbbb
parse error
$
>
I want to know why it could run at the first time, but it could not
run at the second time.

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