无向图邻接表无法成功得到运行结果，显示的是问号

Question

#include
#include
#define MVNum 100
#define OK 1
#define ERROR -1
using namespace std;
typedef char VerTexType;
typedef int Status;

typedef struct ArcNode{
int adjvex;
struct ArcNode *nextarc;
}ArcNode;

typedef struct VNode{
VerTexType data;
ArcNode *firstarc;
}VNode,AdjList[MVNum];

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

Status LocateVex(ALGraph G,VerTexType v){
for(int i=0;i<G.vexnum;++i){
if(G.vertices[i].data==v)
return i;
return ERROR;
}
}
Status CreateUDG(ALGraph &G){
VerTexType v1,v2;
int i,j,k;
cout<<"请输入顶点和边数:";
cin>>G.vexnum>>G.arcnum; //顶点和边数

cout<<"请输入顶点:";
for(i=0;i<G.vexnum;++i){
    cin>>G.vertices[i].data;
    G.vertices[i].firstarc=NULL;    //初始化表头指针 
} 

cout<<"请输入边:"<<endl;
for(k=0;k<G.arcnum;++k){
    ArcNode *p1,*p2;
    cin>>v1>>v2;
    i=LocateVex(G,v1);
    j=LocateVex(G,v2);
    
    p1=new ArcNode;
    p1->adjvex=j;
    p1->nextarc=G.vertices[i].firstarc;    //头插法 
    G.vertices[i].firstarc=p1;
    
    p2=new ArcNode;
    p2->adjvex=i;
    p2->nextarc=G.vertices[j].firstarc;    //头插法 
    G.vertices[j].firstarc=p2;
}
return OK;

}

void Print(ALGraph G)//打印邻接表
{
cout<<"打印邻接表如下：";
cout<<endl;
for(int i=0; i<G.vexnum; i++)//遍历每个顶点的邻接表
{
cout<<G.vertices[i].data;
ArcNode *p=G.vertices[i].firstarc;

    while(p)
    {
        cout<<"->"<<G.vertices[p->adjvex].data;
        p=p->nextarc;
    }
    cout<<endl;
    
}

}

int FirstAdjVex(ALGraph G,int v){

ArcNode *p=G.vertices[v].firstarc;
if(p)    return p->adjvex;

else 
    return ERROR;

}

int NextAdjVex(ALGraph G,int v,int w){
int i;
ArcNode *p=G.vertices[i].firstarc;
while(p){
if(p->adjvex==w) break;

    p=p->nextarc;
}
if(p->adjvex!=w||!p->nextarc)
    return ERROR;
return p->nextarc->adjvex; 

}

bool visited[10];

void DFS(ALGraph G,int v){
int w;
visited[v]=true;
cout<<G.vertices[v].data<<" ";
for(w=FirstAdjVex(G,v);w>=0;w=NextAdjVex(G,v,w))
if(!visited[w])
DFS(G,w);
}

void DFSTraverse(ALGraph G) //深搜
{ int i;
for(i=0;i<G.vexnum;++i)
visited[i]=false; //全部置为未访问

for(i=0;i<G.vexnum;i++)
    if(!visited[i])
        DFS(G, i);

}

void BFSTraverse(ALGraph G) //广搜
{
queue q;
int i;
for(i=0; i<G.vexnum; i++)
visited[i]=false;

for(i=0; i<G.vexnum; i++)
{
    if(!visited[i])
    {
        q.push(i);
        visited[i]=true;
        while(!q.empty())
        {
            int v=q.front();
            q.pop();
            cout<<G.vertices[v].data<<" ";
            for(int w=FirstAdjVex(G, v); w>=0; w=NextAdjVex(G, v, w))
            {
                if (!visited[w])
                {
                    q.push(w);
                    visited[w]=true;
                }
            }

        }
    }

}

}

int main()
{
ALGraph G;
CreateUDG(G);
Print(G);

cout<<"深度遍历：";
DFSTraverse(G);
cout<<endl;

cout<<"广度遍历：";
BFSTraverse(G);
cout<<endl;
return 0;

}