当我使用线程模拟地铁站时，我遇到了分段故障 我想要的想法是，我有4个车站，4个路径和4个列车，每个列车通过一个路径到某个车站，火车通过一个线程移动我的初始模拟工作只是找到，直到我尝试进入第4线程（“火车”）到我的世界，我开始得到分段错误（核心愚蠢） 我把这些作为我的结构：
struct Path {
int Direction; //if equals to 1 it's to the tunnel 0 it's away from the tunnel
int size;
char name[25]; // A or B or C or D
int Used;
};
struct train {
int TrainId;
int speed;
int position;
int direction;
struct Path CurPath;
};
一些路径初始化程序
struct Path PathA; //Path A inital Info
PathA.Direction = 1 ;
strcpy( PathA.name, "A");
PathA.size = 20;
paths[0]=PathA;
一些火车初始化者：
train1->speed = 20;
train1->CurPath = PathA;
train1->TrainId = 1;
train1->direction = 1;
train1->position = 0;
pthread_create(&train1Th, NULL, run, (void *)train1);
和线程的run方法：
void *run (void *Train){
//sleep(1);
int i;
struct train *Trains= (struct train*)Train;
if((*Trains).TrainId == 1)
i=0;
if((*Trains).TrainId == 2)
i=2;
if((*Trains).TrainId == 3)
i=0;
if((*Trains).TrainId == 4)
i=2;
while(run){
sleep(1);
if((*Trains).TrainId == 1)
if (i==8) i=0;
if((*Trains).TrainId == 2)
if (i==6) i=2;
if((*Trains).TrainId == 3)
if (i>8) i=0;
if((*Trains).TrainId == 4)
if (i>8) i=0;
(*Trains).CurPath = paths[i];
paths[i].Used = 0;
if((*Trains).CurPath.Used == 1){ puts("Busy waiting");
sleep(2);}
printf("\nThe Train is on path : %s,is now at the endpoint with an id of %d", (*Trains).CurPath.name, (*Trains).TrainId);
paths[i].Used == 1;
if((*Trains).TrainId == 1)
i=i+4;
if((*Trains).TrainId == 2)
i=i+2;
if((*Trains).TrainId == 3)
i=i+7;
if((*Trains).TrainId == 4)
i=i+5;
}
其中i仅用于路径选择 尝试添加新火车时导致分段错误的原因是什么？ 这是我的代码整体的副本：
#include <stdio.h>
#include <string.h>
#include <pthread.h>
#include <stdlib.h>
#include <time.h>
#include<sys/time.h>
int semtime =20;
struct Path {
int Direction; //if equals to 1 it's to the tunnel 0 it's away from the tunnel
int size;
char name[25]; // A or B or C or D
int Used;
};
struct train {
int TrainId;
int speed;
int position;
int direction;
struct Path CurPath;
};
struct Path paths[8];
void *run (void *Train){
//sleep(1);
int i;
struct train *Trains= (struct train*)Train;
if((*Trains).TrainId == 1)
i=0;
if((*Trains).TrainId == 2)
i=2;
if((*Trains).TrainId == 3)
i=0;
if((*Trains).TrainId == 4)
i=2;
while(run){
sleep(1);
if((*Trains).TrainId == 1)
if (i==8) i=0;
if((*Trains).TrainId == 2)
if (i==6) i=2;
if((*Trains).TrainId == 3)
if (i>8) i=0;
if((*Trains).TrainId == 4)
if (i>8) i=0;
(*Trains).CurPath = paths[i];
paths[i].Used = 0;
if((*Trains).CurPath.Used == 1){ puts("Busy waiting");
sleep(2);}
printf("\nThe Train is on path : %s,is now at the endpoint with an id of %d", (*Trains).CurPath.name, (*Trains).TrainId);
paths[i].Used == 1;
if((*Trains).TrainId == 1)
i=i+4;
if((*Trains).TrainId == 2)
i=i+2;
if((*Trains).TrainId == 3)
i=i+7;
if((*Trains).TrainId == 4)
i=i+5;
}
//printf("%02d:%02d:%02d\n", tm->tm_hour, tm->tm_min, tm->tm_sec);
/* time_t now = time( NULL);
struct tm now_tm = *localtime( &now);
struct tm then_tm = now_tm;
then_tm.tm_sec += semtime; // add 50 seconds to the time
mktime( &then_tm); // normalize it
printf( "%s\n", asctime( &now_tm));
printf( "%s\n", asctime( &then_tm));
*/
return NULL;
}
int main( ) {
/* Initilizing Paths */
struct Path PathA; //Path A inital Info
PathA.Direction = 1 ;
strcpy( PathA.name, "A");
PathA.size = 20;
paths[0]=PathA;
struct Path PathA2; //Path A inital Info The other direction
PathA.Direction = 0 ;
strcpy( PathA.name, "A");
PathA.size = 20;
paths[1]=PathA2;
struct Path PathB; //Path B inital Info
malloc(sizeof(struct Path));
PathB.Direction = 1 ;
strcpy( PathB.name, "B");
PathB.size = 20;
paths[2]=PathB;
struct Path PathB2; //Path A inital Info The other direction
PathB2.Direction = 0 ;
strcpy( PathB2.name, "B");
PathB2.size = 20;
paths[3]=PathB2;
struct Path PathC; //Path c inital Info
PathC.Direction = 1 ;
strcpy( PathC.name, "C");
PathC.size = 20;
paths[4]=PathC;
struct Path PathC2; //Path C inital Info The other direction
PathC2.Direction = 0 ;
strcpy( PathC2.name, "C");
PathC2.size = 20;
paths[5]=PathC2;
struct Path PathD; //Path D inital Info
PathD.Direction = 1 ;
strcpy( PathD.name, "D");
PathD.size = 20;
paths[6]=PathD;
struct Path PathD2; //Path D inital Info The other direction
PathD2.Direction = 0 ;
strcpy( PathD2.name, "D");
PathD2.size = 20;
paths[7]=PathD;
struct train *train1;
pthread_t train1Th;
train1->speed = 20;
train1->CurPath = PathA;
train1->TrainId = 1;
train1->direction = 1;
train1->position = 0;
pthread_create(&train1Th, NULL, run, (void *)train1);
struct train *train2;
pthread_t train2Th;
train2->speed = 20;
train2->CurPath = PathB;
train2->TrainId = 2;
train2->direction = 1;
train2->position = 0;
pthread_create(&train2Th, NULL, run, (void *)train2);
struct train *train3;
pthread_t train3Th;
train3->speed = 20;
train3->CurPath = PathA;
train3->TrainId = 3;
train3->direction = 1;
train3->position = 0;
pthread_create(&train3Th, NULL, run, (void *)train3);
struct train *train4;
train4->TrainId = 4;
return 0;
}
当我尝试访问TrainId时发生错误
答案 0 :(得分：1)
如评论中所述，您尝试影响未分配内存的值：
struct train *train1;
// you declare a pointer to a structure train, but your struct does not exists in memory
train1->speed = 20;
// and then, you initialize an unallocated memory with a value
最简单的可能是使用train结构而不是指向结构的指针（你将避免分配和释放内存的问题）并在启动线程时给出结构的地址：
struct train train1;
train1.speed = 20;
[...]
pthread_create(&train1Th, NULL, run, (void *)&train1);