二重指针出现异常，求解

二重指针出现错误，求解啊
# include <stdio.h>
# include <string.h>
# include <stdlib.h>
# include <malloc.h>
# include <conio.h>

# define MAX_VERTEX_NUM 200
# define MAX_ARC_NUM 2000
# define OK 1
typedef int VertexType;
typedef int InfoType;

typedef struct cities
{
int Locate;
char country[256];
char city[256];
double Latitude;
double Longtitude;

}CityNode;
typedef struct routes
{
char FromCity[256];
char ToCity[256];
char Transport[256];
double Time;
double Cost;
double Weight;
}RouteNode;

typedef struct ArcNode//define structure ALGraph
{ int adjvex;
struct ArcNode *nextarc;
RouteNode *info;
}ArcNode;

typedef struct VNode
{ CityNode data;
ArcNode *firstarc;
}VNode,AdjList[MAX_VERTEX_NUM];

typedef struct
{ AdjList vertices;
int vexnum,arcnum;
int kind;
}ALGraph;

int CreateDG(ALGraph &G){ //CreateDG() subfunction int IncInfo,i,j,k,v1,v2
int v1,v2;
FILE* fp1=NULL;
fp1 = fopen ("../cities.txt","r");
if(!fp1){
printf("Can not open the file cities.csv!\n");
exit (0);
}
G.vexnum = 199;
G.arcnum = 1974;

char* str=NULL;
int L=0;
for(int i=0;i<G.vexnum;++i)
{
G.vertices[i].data.Locate = i; //initial G.vertices[i].data
str = (char*) malloc(sizeof(char) * 100);
fgets(str,99,fp1);
L=strlen(str);
for (int j=0;j<L;j++) {
if(str[j]==',')str[j]=' ';
}
sscanf(str,"%s %s %lf %lf",G.vertices[i].data.country,G.vertices[i].data.city,
&G.vertices[i].data.Latitude,&G.vertices[i].data.Longtitude);

G.vertices[i].firstarc=NULL;//initial G.vertices[i].firstarc
}

FILE* fp2=NULL;
fp2 = fopen ("../routes.txt","r");
if(!fp2){
printf("Can not open the file routes.csv!\n");
exit (0);
}

char from[256];
char to[256];
char tranpt[128];
double time,cost;

ArcNode **p; //定义二重指针
p=(ArcNode **)malloc(G.arcnum*sizeof(ArcNode*));
for(i=0;i<G.arcnum;++i)//input arc(v1,v2)
{
str = (char*) malloc(sizeof(char) * 100);
fgets(str,99,fp2);
L=strlen(str);
for (int j=0;j<L;j++) {
if(str[j]==',')str[j]=' ';
}
sscanf(str,"%s %s %s %lf %lf %lf",from,to,tranpt,&time,&cost);

int k=0;
while(strcmp(from,G.vertices[k].data.city)&&k<G.vexnum){
k++;
}
v1 = G.vertices[k].data.Locate;

k=0;
while(strcmp(to,G.vertices[k].data.city)&&k<G.vexnum){
k++;
}
v2 = G.vertices[k].data.Locate;

v1--;
v2--;

p[i]=(ArcNode *)malloc(sizeof(ArcNode));//allocate memory
if(!p)
{
printf("Overflow!\n");
return (0);
}
p[i]->adjvex=v2;//assign p->adjvex
p[i]->nextarc=G.vertices[v1].firstarc;
strcpy(p[i]->info->FromCity,from); //调试至此出现AccessViolation ！求解！！！
strcpy(p[i]->info->ToCity,to);
strcpy(p[i]->info->Transport,tranpt);
p[i]->info->Time = time;
p[i]->info->Cost = cost;

p[i]->info->Weight = 0.3*(p[i]->info->Time)+0.7*(p[i]->info->Cost);//权重按照时间与费用三七开
G.vertices[v1].firstarc=p[i];

} //for end
return (OK);
} //CreateDG() end

[解决办法]
崩溃的时候在弹出的对话框按相应按钮进入调试，按Alt+7键查看Call Stack里面从上到下列出的对应从里层到外层的函数调用历史。双击某一行可将光标定位到此次调用的源代码或汇编指令处。

[解决办法]

帮你把代码整理下格式，你那个cities.csv文件我没有，没法帮你调试噢



#include &lt;stdio.h&gt;
#include &lt;string.h&gt;
#include &lt;stdlib.h&gt;

#define MAX_VERTEX_NUM 200
#define MAX_ARC_NUM  2000
#define OK 1

typedef int VertexType;
typedef int InfoType;


typedef struct cities
{
    int Locate;
    char country[256];
    char city[256];
    double Latitude;
    double Longtitude;
} CityNode;

typedef struct routes
{
    char FromCity[256];
    char ToCity[256];
    char Transport[256];
    double Time;
    double Cost;
    double Weight;
} RouteNode;

typedef struct ArcNode //define structure ALGraph
{
    int adjvex;
    struct ArcNode *nextarc;
    RouteNode *info;
} ArcNode;

typedef struct VNode
{
    CityNode data;
    ArcNode *firstarc;
} VNode, AdjList[MAX_VERTEX_NUM];

typedef struct
{
    AdjList vertices;
    int vexnum,arcnum;
    int kind;
} ALGraph;




int CreateDG(ALGraph &G)
{
    //CreateDG() subfunction  int IncInfo,i,j,k,v1,v2 
 
    
    int v1,v2;
    FILE* fp1=NULL;
    fp1 = fopen ("../cities.txt","r");
    if(!fp1)
    {
        printf("Can not open the file cities.csv!\n");
        exit (0);
    }
    G.vexnum = 199;
    G.arcnum = 1974;

    char* str=NULL;
    int L=0;
    int i;
    for(i=0;i&lt;G.vexnum;++i)
    {    
        G.vertices[i].data.Locate = i;  //initial G.vertices[i].data
        str = (char*) malloc(sizeof(char) * 100);
        fgets(str,99,fp1);
        L=strlen(str);
        for (int j=0;j&lt;L;j++)
        {
            if(str[j]==',')
            {
                str[j]=' ';
            }
        }
        sscanf(str,"%s %s %lf %lf",G.vertices[i].data.country,G.vertices[i].data.city,
        &G.vertices[i].data.Latitude,&G.vertices[i].data.Longtitude);

        G.vertices[i].firstarc=NULL;//initial G.vertices[i].firstarc
    }

    FILE* fp2 = NULL;
    fp2 = fopen ("../routes.txt","r");
    if(!fp2)
    {
        printf("Can not open the file routes.csv!\n");
        exit (0);
    }


    char from[256];
    char to[256];
    char tranpt[128];
    double time,cost;

    ArcNode **p;          //定义二重指针
    p=(ArcNode **)malloc(G.arcnum*sizeof(ArcNode*));
    for(i=0;i&lt;G.arcnum;++i)//input arc(v1,v2)
    {
        str = (char*) malloc(sizeof(char) * 100);
        fgets(str,99,fp2);
        L=strlen(str);
        for (int j=0;j&lt;L;j++)
        {
            if(str[j]==',')
            {
                str[j]=' ';
            }
        } 
 
        
        sscanf(str,"%s %s %s %lf %lf",from,to,tranpt,&time,&cost);

        int k=0;
        while(strcmp(from,G.vertices[k].data.city) && k&lt;G.vexnum)
        {
            k++;
        }
        
        v1 = G.vertices[k].data.Locate;

        k=0;
        while(strcmp(to,G.vertices[k].data.city)&&k&lt;G.vexnum)
        {
            k++;
        }
        v2 = G.vertices[k].data.Locate;

        v1--;
        v2--;
        
        p[i]=(ArcNode *)malloc(sizeof(ArcNode));//allocate memory
        if(!p)
        {
            printf("Overflow!\n");
            return (0);
        }
        
        p[i]-&gt;adjvex=v2; //assign p-&gt;adjvex
        p[i]-&gt;nextarc=G.vertices[v1].firstarc;
        strcpy(p[i]-&gt;info-&gt;FromCity,from);  //调试至此出现AccessViolation ！求解！！！
        strcpy(p[i]-&gt;info-&gt;ToCity,to);
        strcpy(p[i]-&gt;info-&gt;Transport,tranpt);
        p[i]-&gt;info-&gt;Time = time;
        p[i]-&gt;info-&gt;Cost = cost;

        p[i]-&gt;info-&gt;Weight = 0.3*(p[i]-&gt;info-&gt;Time)+0.7*(p[i]-&gt;info-&gt;Cost);//权重按照时间与费用三七开
        G.vertices[v1].firstarc=p[i];
    } //for end
    
    return (OK);
} //CreateDG() end

int main(int argc, char *argv[])
{
    ALGraph G;
    CreateDG(G);
    return 0;
}

[解决办法]

        p[i]=(ArcNode *)malloc(sizeof(ArcNode));    //allocate memory
        if(!p)    //上面是对p[i]申请空间，这儿为什么变成了对p的判断，应该是if (!p[i])吧，或者if (p[i] == NULL)
        {
            printf("Overflow!\n");
            return (0);
        }

二重指针出现异常求解

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