我收到了很多错误，我根本无法运行，代码不是我的（代码是在线提供的）。
是我的标题是问题吗？我知道问题非常广泛，但我是C的新手，这些错误给我带来了一些麻烦。我并没有期待太多，但是如果有人能够指出我正确的方向，那就太棒了......
node0.c
#include <stdio.h>
#include "prog3.h"
extern struct rtpkt {
int sourceid; /* id of sending router sending this pkt */
int destid; /* id of router to which pkt being sent
(must be an immediate neighbor) */
int mincost[4]; /* min cost to node 0 ... 3 */
};
extern int TRACE;
extern int YES;
extern int NO;
struct distance_table
{
int costs[4][4];
} dt0;
/* students to write the following two routines, and maybe some others */
void rtinit0()
{
}
void rtupdate0(rcvdpkt)
struct rtpkt *rcvdpkt;
{
}
printdt0(dtptr)
struct distance_table *dtptr;
{
printf(" via \n");
printf(" D0 | 1 2 3 \n");
printf(" ----|-----------------\n");
printf(" 1| %3d %3d %3d\n",dtptr->costs[1][1],
dtptr->costs[1][2],dtptr->costs[1][3]);
printf("dest 2| %3d %3d %3d\n",dtptr->costs[2][1],
dtptr->costs[2][2],dtptr->costs[2][3]);
printf(" 3| %3d %3d %3d\n",dtptr->costs[3][1],
dtptr->costs[3][2],dtptr->costs[3][3]);
}
linkhandler0(linkid, newcost)
int linkid, newcost;
/* called when cost from 0 to linkid changes from current value to newcost*/
/* You can leave this routine empty if you're an undergrad. If you want */
/* to use this routine, you'll need to change the value of the LINKCHANGE */
/* constant definition in prog3.c from 0 to 1 */
{
}
节点1
#include <stdio.h>
#include "prog3.h"
extern struct rtpkt {
int sourceid; /* id of sending router sending this pkt */
int destid; /* id of router to which pkt being sent
(must be an immediate neighbor) */
int mincost[4]; /* min cost to node 0 ... 3 */
};
extern int TRACE;
extern int YES;
extern int NO;
int connectcosts1[4] = { 1, 0, 1, 999 };
struct distance_table
{
int costs[4][4];
} dt1;
/* students to write the following two routines, and maybe some others */
rtinit1()
{
}
rtupdate1(rcvdpkt)
struct rtpkt *rcvdpkt;
{
}
printdt1(dtptr)
struct distance_table *dtptr;
{
printf(" via \n");
printf(" D1 | 0 2 \n");
printf(" ----|-----------\n");
printf(" 0| %3d %3d\n",dtptr->costs[0][0], dtptr->costs[0][2]);
printf("dest 2| %3d %3d\n",dtptr->costs[2][0], dtptr->costs[2][2]);
printf(" 3| %3d %3d\n",dtptr->costs[3][0], dtptr->costs[3][2]);
}
linkhandler1(linkid, newcost)
int linkid, newcost;
/* called when cost from 1 to linkid changes from current value to newcost*/
/* You can leave this routine empty if you're an undergrad. If you want */
/* to use this routine, you'll need to change the value of the LINKCHANGE */
/* constant definition in prog3.c from 0 to 1 */
{
}
节点2
#include <stdio.h>
#include "prog3.h"
extern struct rtpkt {
int sourceid; /* id of sending router sending this pkt */
int destid; /* id of router to which pkt being sent
(must be an immediate neighbor) */
int mincost[4]; /* min cost to node 0 ... 3 */
};
extern int TRACE;
extern int YES;
extern int NO;
struct distance_table
{
int costs[4][4];
} dt2;
/* students to write the following two routines, and maybe some others */
void rtinit2()
{
}
void rtupdate2(rcvdpkt)
struct rtpkt *rcvdpkt;
{
}
printdt2(dtptr)
struct distance_table *dtptr;
{
printf(" via \n");
printf(" D2 | 0 1 3 \n");
printf(" ----|-----------------\n");
printf(" 0| %3d %3d %3d\n",dtptr->costs[0][0],
dtptr->costs[0][1],dtptr->costs[0][3]);
printf("dest 1| %3d %3d %3d\n",dtptr->costs[1][0],
dtptr->costs[1][1],dtptr->costs[1][3]);
printf(" 3| %3d %3d %3d\n",dtptr->costs[3][0],
dtptr->costs[3][1],dtptr->costs[3][3]);
}
节点3
#include <stdio.h>
#include "prog3.h"
extern struct rtpkt {
int sourceid; /* id of sending router sending this pkt */
int destid; /* id of router to which pkt being sent
(must be an immediate neighbor) */
int mincost[4]; /* min cost to node 0 ... 3 */
};
extern int TRACE;
extern int YES;
extern int NO;
struct distance_table
{
int costs[4][4];
} dt3;
/* students to write the following two routines, and maybe some others */
void rtinit3()
{
}
void rtupdate3(rcvdpkt)
struct rtpkt *rcvdpkt;
{
}
printdt3(dtptr)
struct distance_table *dtptr;
{
printf(" via \n");
printf(" D3 | 0 2 \n");
printf(" ----|-----------\n");
printf(" 0| %3d %3d\n",dtptr->costs[0][0], dtptr->costs[0][2]);
printf("dest 1| %3d %3d\n",dtptr->costs[1][0], dtptr->costs[1][2]);
printf(" 2| %3d %3d\n",dtptr->costs[2][0], dtptr->costs[2][2]);
}
头文件
/* libraries */
#include <stdlib.h>
/* definitions */
#define INF 999
#ifndef FALSE
#define FALSE (0)
#endif
#ifndef TRUE
#define TRUE (!FALSE)
#endif
struct rtpkt {
int sourceid; /* id of sending router sending this pkt */
int destid; /* id of router to which pkt being sent
(must be an immediate neighbor) */
int mincost[4]; /* min cost to node 0 ... 3 */
};
struct event {
float evtime; /* event time */
int evtype; /* event type code */
int eventity; /* entity where event occurs */
struct rtpkt *rtpktptr; /* ptr to packet (if any) assoc w/ this event */
struct event *prev;
struct event *next;
};
struct distance_table
{
int costs[4][4];
int link[4];
};
/* forward declarations */
void init();
void tolayer2(struct rtpkt packet);
void insertevent(struct event *p);
void rtupdate0(struct rtpkt *rcvdpkt);
void rtupdate1(struct rtpkt *rcvdpkt);
void rtupdate2(struct rtpkt *rcvdpkt);
void rtupdate3(struct rtpkt *rcvdpkt);
void linkhandler0(int linkid, int newcost);
void linkhandler1(int linkid, int newcost);
void rtinit0();
void rtinit1();
void rtinit2();
void rtinit3();
void sendpkt0();
void sendpkt1();
void sendpkt2();
void sendpkt3();
void printdt0(struct distance_table *dtptr);
void printdt1(struct distance_table *dtptr);
void printdt2(struct distance_table *dtptr);
void printdt3(struct distance_table *dtptr);
主： http://gaia.cs.umass.edu/kurose/network/prog3.c
我在顶部添加了以下内容：
#include "stdafx.h"
#include "prog3.h"
答案 0 :(得分：1)
Haven仔细观察是否是你唯一的问题，但重新定义错误无疑是来自于在每个c文件顶部包含标题而没有任何预编译器检查来确定标题＆＃ 39; s符号已经被声明。
将这样的内容放在标题的顶部：
#ifndef _PROG3_H
#define _PROG3_H
在标题文件的底部：
#endif
这确保了如果编译器单独检查每个文件，编译器就知道您已声明了所需的符号。但是，如果所有文件都链接在一起，则不会为尝试链接的每个目标文件定义一次头文件中的所有符号。
编辑：现在我已经查看了一些代码，虽然我提到的头文件问题肯定需要解决，但它并不是你重新定义事物的唯一地方。您一次又一次地在C文件中将rtpkt声明为extern，即使您还从头文件中包含了它的定义。如果它在标题中，您也不想将它放在C文件中。我看到你有distance_table定义了很多次。同样，如果它位于标题中并以这种方式包含，请不要在C文件中重新定义它。