Problems Compiling - c

Question

So I have to create a compiler for the Tiny C language, but I cant compile it, I have the .y and .l files and both work all right, but when I try to compile the .tab.c file, it shows 3 errors for
undefined reference to 'install_id'
undefined reference to printSymtab'
undefined reference to 'lookup_id'
Here are the codes:
Symtab.h
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct symtab_node * SYMTAB;
typedef struct symtab_node {
char * nombre;
int type;
float fval;
SYMTAB next;
} SYMTAB_NODE;
SYMTAB lookup_id(SYMTAB st, char * name);
SYMTAB install_id(SYMTAB st, char * name, int typ);
void printSymtab(SYMTAB t);
Symtab.c
#include "symtab.h"
#include <stdio.h>
int next_num() {
static int i = 1;
return i++;
}
/* looks up an is in ST. Returns pointer to cell if found else NULL */
SYMTAB lookup_id(SYMTAB st, char * name) {
SYMTAB tmp = st;
if (tmp == NULL) {/* empty list */
return NULL;
} else {
while (tmp != NULL) {
if (strcmp(tmp->idname,name) == 0) {
return tmp; /* found */
} else {
tmp = tmp->next; /* go to next cell */
}
}
return NULL; /* not found */
}
}
/* adds an id to ST if not present */
SYMTAB install_id(SYMTAB st, char * name, int typ) {
if (lookup_id(st, name) == NULL) {
SYMTAB nst = (SYMTAB)malloc(sizeof(SYMTAB_NODE));
nst->idname = (char *) strdup(name);
nst->idnum = next_num();
nst->next = st;
return nst;
} else {
return st;
}
}
/* print out ST */
void printSymtab(SYMTAB t) {
SYMTAB tmp = t;
while (tmp != NULL) {
printf("%s\t%d\n", tmp->idname, tmp->idnum);
tmp = tmp->next;
}
}
grammar.y
%{
#include "symtab.h"
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
char * concat (char * str1, char * str2);
extern int yylex();
extern char * yytext;
extern int yylineno;
SYMTAB st;
int typev;
/* Function definitions */
void yyerror (char *string);
%}
%union{
char *strval;
int value;
float fvalue;
SYMTAB st;
}
/* Declaramos todos los tokens que recibirá el programa y que provienen del cparser.l */
%token SEMI INTEGER FLOAT
%token IF THEN ELSE WHILE DO
%token READ WRITE
%token LPAREN RPAREN LBRACE RBRACE
%token LT EQ
%token PLUS MINUS TIMES DIV ASSIGN
%token<value> INT_NUM
%token<fvalue> FLOAT_NUM
%token<strval> ID
%%
/* Definimos las reglas de producción para el mini-lenguaje C */
program: var_dec stmt_seq { printf ("No hay errores sintacticos\n");}
;
var_dec: var_dec single_dec
|
;
single_dec: type ID SEMI { st = install_id(st,$2,typev); printSymtab(st); }
;
type: INTEGER { typev = 1; }
| FLOAT { typev = 2; }
;
stmt_seq: stmt_seq stmt
|
;
stmt: IF exp THEN else
| WHILE exp DO stmt
| variable ASSIGN exp SEMI { /*st = install_id(st,$1); */}
| READ LPAREN variable RPAREN SEMI { /*st = install_id(st,$3); */}
| WRITE LPAREN exp RPAREN SEMI
| block
| error SEMI { yyerrok;}
;
else: stmt
| ELSE stmt
;
block: LBRACE stmt_seq RBRACE
;
exp: simple_exp LT simple_exp
| simple_exp EQ simple_exp
| simple_exp
;
simple_exp: simple_exp PLUS term
| simple_exp MINUS term
| term
;
term: term TIMES factor
| term DIV factor
| factor
;
factor: LPAREN exp RPAREN
| INT_NUM
| FLOAT_NUM
| variable
;
variable: ID
{ if(lookup_id(st,$1) == NULL){
yyerror(concat("Error: Undeclared Identifier ", $1));
}
}
;
%%
/* A function that concatenates two strings and returns the result */
char * concat(char * str1, char * str2){
char *str3;
str3 = (char *) calloc(strlen(str1)+strlen(str2)+1, sizeof(char));
strcpy(str3,str1);
strcat(str3,str2);
return str3;
}
#include "lex.yy.c"
/* Bison does NOT implement yyerror, so define it here */
void yyerror (char *string){
printf ("ERROR NEAR LINE %d: %s\n",yylineno,string);
}
/* Bison does NOT define the main entry point so define it here */
main (){
yyparse();
yylex();
}
lexem.y
%{
#include <string.h>
#include <stdlib.h>
char * strval;
int value;
float fvalue;
int error;
extern YYSTYPE yylval;
%}
/* This is the rule definition */
%option noyywrap
%option yylineno
ids [A-Za-z_][A-Za-z0-9_]*
digits 0|[1-9][0-9]*|0(c|C)[0-7]+|0(x|X)[0-9A-Fa-f]+
floats [0-9]*"."[0-9]+([eE][-+]?[0-9]+)?
%%
/* Consume los comentarios*/
(\/\*([^\*]|\*[^/])*\*\/)|(\/\/.*)
/* Consume los espacios, tabulaciones y saltos de linea*/
[[:space:]]|[[:blank:]]|\n
/* Palabras reservadas */
"int" { return INTEGER; }
"float" { return FLOAT; }
"if" { return IF; }
"then" { return THEN; }
"else" { return ELSE; }
"do" { return DO; }
"while" { return WHILE; }
"read" { return READ; }
"write" { return WRITE; }
/* Simbolos de puntuacion, operadores y relacionales */
/* Puntuacion */
";" { return SEMI; }
"(" { return LPAREN; }
")" { return RPAREN; }
"{" { return LBRACE; }
"}" { return RBRACE; }
/* Relacionales */
">" { return LT; }
"==" { return EQ; }
/* Operadores */
"+" { return PLUS; }
"-" { return MINUS; }
"*" { return TIMES; }
"/" { return DIV; }
"=" { return ASSIGN; }
{ids} { yylval.strval = (char *) strdup(yytext);
return (ID); }
{digits} { yylval.value = atoi(yytext);
return (INT_NUM); }
{floats} { yylval.fvalue = atof(yytext);
return (FLOAT_NUM); }
/* Consume los simbolos que sobran y marca error */
. { printf("LEXICAL ERROR NEAR LINE %d: %s \n", yyget_lineno(), yyget_text()); error++; }
%%

Answer 1

You're not supposed to compile the whatever.tab.h file, that's a header file containing the YACC elements for the grammar, for inclusion into the lex and yacc code sections, as well as your own code if you need access to it.
You're supposed to compile whatever.tab.c, ensuring that you're also including your symtab.c (or its equivalent object file), and any other C source files as well.
And, based on your comment, it's this non-inclusion of the symtab.c file which is indeed causing your immediate error.
When I execute your steps (slightly modified for different names):
flex lexem.l
yacc -d -v grammar.y
gcc -o par y.tab.c
then I get a similar problem to what you're seeing:
/tmp/ccI5DpZQ.o:y.tab.c:(.text+0x35c): undefined reference to `install_id'
/tmp/ccI5DpZQ.o:y.tab.c:(.text+0x36e): undefined reference to `printSymtab'
/tmp/ccI5DpZQ.o:y.tab.c:(.text+0x3a7): undefined reference to `lookup_id'
However, when I incorporate the symtab.c file into the compile line (and add the idname and idnum missing bits to the structure in symtab.h to solve compilation problems), it works just fine:
gcc -o par y.tab.c symtab.c
So that's what you need to do, include symtab.c on the gcc command line.