有关C++文件的输入和输出问题

学习C++时遇到的问题
下面这段代码的作用是读取文本中的信息，然后对人名和对应捐款做一定处理，例如下面这段文字：
4
Sam
2000
Freida
100500
Tammy
5000
Rich
55000

我有点不理解“ inFile.getline(str, 1); ”是在干什么，我调试时发现str的值是‘\000’

img

#include <iostream>  
#include <string>  
#include <fstream>
using namespace std;
struct donation 
{
    char name[30];
    double money;
};
int main() 
{
    ifstream inFile;
    cout << "Please enter the name of your file: ";
    char filename[30];
    cin.getline(filename, 30);
    inFile.open(filename);
 
    int num;
    inFile >> num;
    char str[30];
    inFile.getline(str, 1);
    donation *d = new donation[num];
    int bigger = 0;
 
    for (int i = 0; i< num; i++) 
    {
        inFile.getline(d[i].name, 30);
        inFile >> d[i].money;
        inFile.getline(str, 1);
        if (d[i].money>10000) 
        {
            bigger++;
        }
    }
 
    if (bigger > 0 && bigger < num) 
    {
        cout << "Grand Patrons" << endl;
        for (int i = 0; i < num; i++) 
        {
            if (d[i].money>10000) 
            {
            cout << d[i].name << "\t" << d[i].money << endl;
            }
        }
        cout << "Patrons" << endl;
        for (int i = 0; i < num; i++)
        {
            if (d[i].money <= 10000)
            {
            cout << d[i].name << "\t" << d[i].money << endl;
            }
        }
    }
 
    if (bigger == 0) 
    {
        cout << "Grand Patrons" << endl;
        cout << "none" << endl;
        cout << "Patrons" << endl;
        for (int i = 0; i < num; i++)
        {
            if (d[i].money <= 10000)
            {
            cout << d[i].name << "\t" << d[i].money << endl;
            }
        }
    }
 
    if (bigger == num)
    {
        cout << "Grand Patrons" << endl;
        for (int i = 0; i < num; i++){
            if (d[i].money>10000)
            {
            cout << d[i].name << "\t" << d[i].money << endl;
            }
        }
        cout << "Patrons" << endl;
        cout << "none" << endl;
    }
 
    delete[]d;
    inFile.close();
    return 0;
}