c++学生成绩管理代码，运行是乱码，求高手指正

// Note:Your choice is C++ IDE
#include <iostream>
#include<iomanip>
using namespace std;

class English{
    int ptr;
    int score[20];
   
    public:
    void getdata(int val,int ptr) {score[ptr]=val;}
    int disp(int ptr) {return score[ptr];}
};

class Chinese{
    int ptr;
    int score[20];
   
    public:
    void getdata(int val,int ptr) {score[ptr]=val;}
    int disp(int ptr) {return score[ptr];}
};

class Computer{
    int ptr;
    int score[20];
   
    public:
    void getdata(int val,int ptr) {score[ptr]=val;}
    int disp(int ptr) {return score[ptr];}
};

class student:private English,private Chinese,private Computer{
    char name[20][10];
    double average[20];
    static int rank;
   
    public:
    void getdata(int index)
    {
        
        int score1,score2,score3;
        for(int i=0;i<index;i++)
        {
            average[i]=0;
            cout<<"student's name:";
            cin>>name[i];
            cout<<"The score of English Chinese Computer:";
            cin>>score1>>score2>>score3;
            
            English::getdata(score1,i);
            Chinese::getdata(score2,i);
            Computer::getdata(score3,i);
            average[i]=(score1+score2+score3)/3;
        }
    }


void sort(int index)
{
    int i,j,pick;
    for(i=0;i<index;i++)
    {
        pick=0;
        while(average[pick]=-1&&pick<index) {pick++;}
        
        for(j=1;j<index;j++)
        {
            while(average[pick]=-1&&j<index) {j++;}
            if(j<index&&average[j]>average[pick])
                pick=j;
        }
        
        cout<<setw(3)<<rank++<<" ";
        cout<<name[pick]<<endl;
         /*cout<<setw(6)<<name[pick];
        cout<<setw(5)<<English::disp(pick)<<" ";
        cout<<setw(7)<<Chinese::disp(pick)<<" ";
        cout<<setw(5)<<Computer::disp(pick)<<" ";   
                cout<<setw(10)<<setprecision(4)<<average<<endl;*/
        average[pick]=-1;
        
    }
}
};

int student::rank=1;
int main()
{
    student A;
    int num;
   
    cout<<"enter the number:";
    cin>>num;
   
    A.getdata(num);
    cout<<"the result is\n";
   
    cout<<setw(4)<<"rank"<<setw(6)<<"name"<<setw(6)<<"English"
    <<setw(6)<<"Chinese"<<setw(6)<<"Computer"<<setw(10)<<"average"<<endl;
   
    A.sort(num);
   
   
    return 0;
}