C 如何删除代码中未定义的引用?
我被这个编译错误困住了,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:C 如何删除代码中未定义的引用?,c,makefile,undefined-reference,C,Makefile,Undefined Reference,我被这个编译错误困住了,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 目标h: #ifndef _object_h #define _object_h typedef enum{ NORTH, SOUTH, EAST, WEST } Dire
CFLAGS = -Wall -g
src = ex19.c
all: $(src)
cc $(CFLAGS) -o ex19 $(src)
ex19: object.o
clean:
rm -f ex19
目标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
目标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;
}
}
例19.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;
}
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 $(src)
如果执行make或make all,则命令将扩展为:
cc -Wall -g -o ex19 ex19.c
它尝试仅使用ex19.c生成可执行文件
构建目标ex19从未被调用,因为all没有将其作为依赖项。但是,即使这样做了,或者您手动编写makeex19,这仍然只会生成object.o,您没有任何命令将ex19.o与object.o链接起来以生成可执行文件
您应该将src=ex19.c更改为src=ex19.c object.c,因为它们都是源文件。您可以去掉ex19:object.o行,因为它在这里是多余的。这个makefile将在一行中编译和链接所有源文件,这很好
如果要更改makefile以对每个.c文件使用编译器的单独调用,因此链接器需要进行第三次调用,则需要进行一些更改,最好是对现有的makefile进行建模。您知道此处的代码转储没有行号吗?抱歉,我更新了行号。谢谢你的回答。这管用!您可以添加一个例子,改变makefile,对每个.c文件分别使用编译器调用,然后使用链接器调用吗?“我很有兴趣了解这一点。”丹尼克雷恩举了一个例子。您可以将其自动化,以便只需提供$src和所有其他规则即可转换该c文件列表,但最好先了解基础知识
cc $(CFLAGS) -o ex19 $(src)
cc -Wall -g -o ex19 ex19.c