c - Makefile for sql parser... writing dependencies -

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i'm implementing sql parser in lex , yacc, in use symbol table kept in separate .h file (sql.h) , in header file have functions declarations. definitions of these functions kept in .c file (sql.c). have included sql.h in sql.c, refer symbols , functions sql.h in both lex file(1.l) , yacc file(1.y).

the problem i'm not able write proper makefile this. i'm getting errors multiple declarations. include file , how write dependencies? please help. have searched solution i'm not getting it.....

update:

i compile code this:

 lex 1.l yacc -d 1.y gcc lex.yy.c y.tab.c sql.c -ll -ly

i following errors after third command of gcc:

 in file included 1.l:5: sql.h:17: warning: ‘sql’ initialized , declared ‘extern’ sql.h:18: warning: ‘sql_sel’ initialized , declared ‘extern’ 1.l: in function ‘maketable’: 1.l:80: warning: assignment incompatible pointer type in file included 1.y:7: sql.h:17: warning: ‘sql’ initialized , declared ‘extern’ sql.h:18: warning: ‘sql_sel’ initialized , declared ‘extern’ sql.c:3: error: redefinition of ‘sql’ sql.h:15: note: previous definition of ‘sql’ here sql.c:4: error: redefinition of ‘sql_sel’ sql.h:16: note: previous definition of ‘sql_sel’ here

sql.h:

#ifndef sql_h #define sql_h #include <string.h> #include <stdio.h> #include <stdlib.h>  struct sym_table {     char *token;     char *value;     struct sym_table *next; };  struct sym_select {     char **cols;         };  extern struct sym_table *sql = null; extern struct sym_select *sql_sel = null;   void addsymbol(char *, char *); void print(struct sym_table *); void showtable(struct sym_table *); void maketable(struct sym_table *, int);

sql.c:

#include "sql.h"  struct sym_table *sql = null; struct sym_select *sql_sel = null;

and definitions of functions declared in sql.h

1.l file:

%{     #include <stdio.h>     #include <stdlib.h>     #include "y.tab.h"     #include "sql.h"     int lineno=1;     void maketable(struct sym_table *, int);     %}

..... , othr lex file

1.y

%{     #include <stdio.h>     #include <stdlib.h>     #include <string.h>     extern int lineno;     extern void yyerror(char *);     #include "sql.h" %}

.... , other yacc file data

can suggest me other way around this?

please post makefile. far understand there's problem code, not makefile. or try make 1.o 1.l , different 1.o 1.y.

normally dependencies should like:

1l.o: 1.l sql.h; # lex invocation 1y.o: 1.y sql.h; # bison invocation sql.o: sql.c sql.h; # cc invocation prog: 1l.o 1y.o sql.o; # ld invocation

probably need depend on tokens' declaration file.

edit: ah, need put definition of table 1 file, , declaration header. must first understand difference between declaration , definition in c. example if have following files:

aaa.h
int arr[]={1};

aaa.c
#include "aaa.h"

bbb.c
#include "aaa.h"

and try cc -o aaa aaa.c bbb.c, multiple definition error. means, actual array must in 1 file, , in header should extern int arr[];

update:

you should remove setting null in sql.h. it's declaration there, there such , such variable somewhere. actual value assigned in sql.c.


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