我遇到了这个编译错误，我想知道如何调试代码。我的程序基本上有以下文件：
生成文件：
CFLAGS = -Wall -g
src = ex19.c
all: $(src)
cc $(CFLAGS) -o ex19 $(src)
ex19: object.o
clean:
rm -f ex19
object.h：
#ifndef _object_h
#define _object_h
typedef enum{
NORTH, SOUTH, EAST, WEST
} Direction;
typedef struct {
char *description;
int (*init)(void *self);
void (*describe)(void *self);
void (*destroy)(void *self);
void *(*move)(void *self, Direction direction);
int (*attack)(void *self, int damage);
} Object;
int Object_init(void *self);
void Object_destroy(void *self);
void Object_describe(void *self);
void *Object_move(void *self, Direction direction);
int Object_attack(void *self, int damage);
void *Object_new(size_t size, Object proto, char *description);
#define NEW(T, N) Object_new(sizeof(T), T##Proto, N)
#define _(N) proto.N
#endif
object.c：
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "object.h"
#include <assert.h>
void Object_destroy(void *self) {
Object *obj = self;
if(obj) {
if(obj->description) free(obj->decription);
free(obj);
}
}
void Object_describe(void *self) {
Object *obj = self;
printf("%s.\n", obj->description);
}
int Object_init(void *self){
// do nothing really
return 1;
}
void *Object_move(void *sefl, Direction direction){
printf("You can't go that direction.\n");
return NULL;
}
int Object_attack(void *self, int damage){
printf("You can't attack that.\n");
return 0;
}
void *Object_new(size_t size, Object proto, char *description){
// setup the default functions in case they aren't set
if(!proto.init) proto.init = Object_init;
if(!proto.describe) proto.describe = Object_describe;
if(!proto.destroy) proto.destroy = Object_destroy;
if(!proto.attack) proto.attack = Object_attack;
if(!proto.move) proto.move = Object_move;
// this seems weird, but we can make a struct of one size,
// then point a different pointer at it to "cast" it
Object *el = calloc(1, size);
*el = proto;
// copy the description over
el->description = strdup(description);
// initialize it with whatever init we were given
if(!el->init(el)){
// looks like it didn't initialize properly
el->destroy(el);
return NULL;
}
else {
//all done, we made an object of any type
return el;
}
}
ex19.h：
#ifndef __ex19_h
#define __ex19_h
#include "object.h"
struct Monster {
Object proto;
int hit_points;
};
typedef struct Monster Monster;
int Monster_attack(void *self, int damage);
int Monster_init(void *self);
struct Room{
Object proto;
Monster *bad_guy;
struct Room *north;
struct Room *south;
struct Room *east;
struct Room *west;
};
typedef struct Room Room;
void *Room_move(void *self, Direction direction);
int Room_attack(void *self, int damage);
int Room_init(void *self);
struct Map{
Object proto;
Room *start;
Room *location;
};
typedef struct Map Map;
void *Map_move(void *self, Direction direction);
int Map_attack(void *self, int damage);
int Map_init(void *self);
#endif
ex19.c：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include "ex19.h"
int Monster_attack(void *self, int damage){
Monster *monster = self;
printf("You attack %s!\n", monster->_(description));
monster->hit_points -= damage;
if(monster->hit_points > 0) {
printf("It is still alive.\n");
return 0;
}
else{
printf("It is dead!\n");
return 1;
}
}
int Monster_init(void *self){
Monster *monster = self;
monster->hit_points = 10;
return 1;
}
Object MonsterProto = {
.init = Monster_init,
.attack = Monster_attack
};
void *Room_move(void *self, Direction direction) {
Room *room = self;
Room *next = NULL;
if(direction == NORTH && room->north) {
printf("You go north, into:\n");
next = room->north;
}
else if(direction == SOUTH && room->south){
printf("You go south, into:\n");
next = room->south;
}
else if(direction == EAST && room->east){
printf("You go east, into:\n");
next = room->east;
}
else if(direction == WEST && room->west){
printf("You go west, into:\n");
next = room->west;
}
else {
printf("You can't go that direction.");
next = NULL;
}
if(next){
next->_(describe)(next);
}
return next;
}
int Room_attack(void *self, int damage){
Room *room = self;
Monster *monster = room->bad_guy;
if(monster){
monster->_(attack)(monster, damage);
return 1;
}
else{
printf("You flail in the air at nothing. Idiot.\n");
return 0;
}
}
Object RoomProto = {
.move = Room_move,
.attack = Room_attack
};
void *Map_move(void *self, Direction direction){
Map *map = self;
Room *location = map->location;
Room *next = NULL;
next = location->_(move)(location, direction);
if(next) {
map->location = next;
}
return next;
}
int Map_attack(void *self, int damage){
Map* map = self;
Room *location = map->location;
return location->_(attack)(location, damage);
}
int Map_init(void *self){
Map *map = self;
//make some rooms for a small map
Room *hall = NEW(Room, "The great hall");
Room *throne = NEW(Room, "The throne room");
Room *arena = NEW(Room, "The arena, with the minotaur");
Room *kitchen = NEW(Room, "Kitchen, you have the knife now");
// put the bad guy in the arena
arena->bad_guy = NEW(Monster, "The evil minotaur");
// setup the map rooms
hall->north = throne;
throne->west = arena;
throne->east = kitchen;
throne->south = hall;
arena->east = throne;
kitchen->west = throne;
//start the map and the character off in the hall
map->start = hall;
map->location = hall;
return 1;
}
Object MapProto = {
.init = Map_init,
.move = Map_move,
.attack = Map_attack
};
int process_input(Map *game){
printf("\n> ");
char ch = getchar();
getchar(); // eat enter;
int damage = rand() % 4;
switch(ch){
case -1:
printf("Giving up? You such.\n");
return 0;
break;
case 'n':
game->_(move)(game, NORTH);
break;
case 's':
game->_(move)(game, SOUTH);
break;
case 'e':
game->_(move)(game, EAST);
break;
case 'w':
game->_(move)(game, WEST);
break;
case 'a':
game->_(attack)(game, damage);
break;
case 'l':
printf("You can go:\n");
if(game->location->north) printf("NORTH\n");
if(game->location->south) printf("SOUTH\n");
if(game->location->east) printf("EAST\n");
if(game->location->west) printf("WEST\n");
break;
default:
printf("What?: %d\n", ch);
}
return 1;
}
int main(int argc, char *argv[]){
//simple way to setup the randomness
srand(time(NULL));
//make our map to work with
Map *game = NEW(Map, "The hall of the Minotaur.");
printf("You enter the ");
game->location->_(describe)(game->location);
while(process_input(game)) {
}
return 0;
}
编译错误：
cc -Wall -g -o ex19 ex19.c
/tmp/cccuR81O.o：在函数Map_init':
ex19/ex19.c:105: undefined reference to Object_new'中
ex19 / ex19.c：106：对Object_new'
ex19/ex19.c:107: undefined reference to Object_new'的未定义引用
ex19 / ex19.c：108：对Object_new'
ex19/ex19.c:111: undefined reference to Object_new'的未定义引用
ex19 / ex19.c：180：对“Object_new”的更多未定义引用如下
collect2：错误：ld返回1退出状态
make：*** [all]错误1
更新1：有问题的行
105 Room *hall = NEW(Room, "The great hall");
106 Room *throne = NEW(Room, "The throne room");
107 Room *arena = NEW(Room, "The arena, with the minotaur");
108 Room *kitchen = NEW(Room, "Kitchen, you have the knife now");
111 arena->bad_guy = NEW(Monster, "The evil minotaur");
答案 0 :(得分：2)
需要更新makefile以将object.o链接到可执行文件中。目前您的链接行是：
cc $(CFLAGS) -o ex19 $(src)
如果执行make（或make all），则命令将扩展为：
cc -Wall -g -o ex19 ex19.c
尝试仅使用ex19.c生成可执行文件。
永远不会调用构建目标ex19，因为all没有将它作为依赖项。但即使它确实如此，或者您手动编写make ex19，仍然只会object.o，您在任何可以将ex19.o与object.o关联起来的命令都没有可执行文件。
您应该将src = ex19.c更改为src = ex19.c object.c，因为这些都是源文件。你可以取出ex19: object.o行，因为它在这里是多余的。这个makefile将编译并链接一行中的所有源文件，这很好。
如果要更改makefile以对每个.c文件使用编译器的单独调用（因此需要对链接器进行第三次调用），那么您需要进行一些更改，这可能是最好的从现有的模型中模拟你的makefile。