所以我必须为Tiny C语言创建一个编译器，但是我无法编译它，我有.y和.l文件并且都可以正常工作，但是当我尝试编译.tab.c文件时，
显示3个错误以下是代码：
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++; }
%%
答案 0 :(得分：1)
你不应该编译whatever.tab.h文件，那个包含语法的YACC元素的标题文件，用于包含进入lex和yacc代码部分，以及您自己的代码，如果您需要访问它。
您应该编译whatever.tab.c，确保您还包括您的symtab.c（或其等效的目标文件）以及任何其他C源文件。< / p>
根据您的评论，这不包含symtab.c文件，这确实会导致您的即时错误。
当我执行你的步骤时（略微修改了不同的名字）：
flex lexem.l
yacc -d -v grammar.y
gcc -o par y.tab.c
然后我遇到了类似的问题：
/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'
但是，当我将symtab.c文件合并到编译行中时（并将idname和idnum个缺失位添加到symtab.h中的结构以解决编译问题） ，它的工作正常：
gcc -o par y.tab.c symtab.c