C++ Can'；t获取数组内部数组的和

以下数组的和没有正确显示，而是显示了大量数字。我做错了什么

void putdata(){
        int mark_sum;
        cout << name << " " << age << " ";
        for(int i=0;i<6;i++){
            mark_sum += marks[i];
        }
        cout << mark_sum << " ";
        cout <<cur_id - no_of<< endl;
        no_of--;
    }

void putdata（）{
整数马克和；
cout在定义“mark\u sum”时，应将其初始化为零。

在putdata函数的第一行中，只需编写
int-mark\u-sum=0；
即可，而不是
int-mark\u-sum；

问题是，如果不初始化整型变量，则可能无法使用它，因为您不知道该值

详情如下：
Fyi，
mark\u sum+=marks[i]
循环之前，
mark\u sum
的初始值是多少？您从未将其初始化为零。编译器应标记这是“未初始化变量的使用”警告，如果没有，你需要打开你的警告。你也可以尝试实际检查你的IO是否工作，而不是假设它工作。只是说。看起来你真正想要的是。
#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
using namespace std;

//classes
//classes
class Person{
public:
    virtual void getdata() = 0;
    virtual void putdata() = 0;
protected:
    string name;
    int age;
};

class Professor : public Person{
public:
    Professor() {
    }
    void getdata(){
        cin >> name;
        cin >> age >> publications;
        cur_id++;
        no_of++;
    }
    void putdata(){
        cout << name << " ";
        cout << age << " ";
        cout << publications << " ";
        cout <<cur_id - no_of<< endl;
        no_of--;
    }
private:
    int publications;
    static int cur_id;
    static int no_of;
};

class Student : public Person{
public:
    Student(){
    }
    void getdata(){
        cin >> name >> age;
        for(int i=0;i<6;i++){
            cin >> marks[i];
        }
        cur_id++;
        no_of++;
    }
    void putdata(){
        int mark_sum;
        cout << name << " " << age << " ";
        for(int i=0;i<6;i++){
            mark_sum += marks[i];
        }
        cout << mark_sum << " ";
        cout <<cur_id - no_of<< endl;
        no_of--;
    }
private:
    int marks[6];
    static int cur_id;
    static int no_of;
};

//static variables
int Student::cur_id = 0;
int Professor::cur_id = 0;
int Student::no_of = -1;
int Professor::no_of = -1;

//main
int main(){

    int n, val;
    cin>>n; //The number of objects that is going to be created.
    Person *per[n];

    for(int i = 0;i < n;i++){

        cin>>val;
        if(val == 1){
            // If val is 1 current object is of type Professor
            per[i] = new Professor;

        }
        else per[i] = new Student; // Else the current object is of type Student

        per[i]->getdata(); // Get the data from the user.

    }

    for(int i=0;i<n;i++)
        per[i]->putdata(); // Print the required output for each object.

    return 0;

}