在0x5914F3BE抛出异常(基于.dll）

您的问题始于数据文件中写入的错误amount。 修复它：

2
Bob
400
Alice
11000

然后，他们继续说明您无意中读取文件的事实。
请记住：混合operator>>和getline()并不像看起来那么简单。
你看，operator>>IGNORESnewline并space字符，直到找到任何其他字符。
然后，它会读取即将到来的字符，直到遇到下一个newline或space字符，但不会丢弃它。

这就是getline问题所在。getline读取所有内容，直到遇到newline或指定的delim字符。 这意味着，如果您的operator>>在遇到newline后停止，getline不会读取任何内容，因为它会立即遇到newline。

要解决此问题，您需要处理newline字符。 为此，您可以先检查流中的下一个字符是否确实newline，然后对其使用istream::ignore();

int next_char = stream.peek();
if(next_char == 'n'){
stream.ignore();
}

代码的一个工作示例是：

#include <iostream>
#include <fstream>
#include <string>
using namespace std;
//Suggestion: class/struct names should start with a capital letter.
struct Donor{
//Suggestion: Use member initializer lists to specify default values.
Donor() : name(), contribution(0){}
string name;
double contribution;
};
int main(){
cout << "Enter the filename: ";
string filename;
cin >> filename;
//Suggestion: Open the file immediately with the filename and use `operator bool` to check if it opened.
ifstream inFile(filename);
if(!inFile){
cout << "Could not open the file " << filename << 'n';
cout << "Program terminating.n";
exit(EXIT_FAILURE);
}
int amount;
inFile >> amount; //! Leaves 'n'
Donor* donors = new Donor[amount];
for(int i = 0; i < amount; ++i){
switch(inFile.peek()){
case 'n': inFile.ignore();
break;
case  EOF: cout << "Donor amount too big!n";
exit(EXIT_FAILURE); 
}
getline(inFile, donors[i].name);
inFile >> donors[i].contribution;
}
cout << "Here's the list of Grand Patrons:n";
bool grandpatrons_exist = false;
for(int i = 0; i < amount; ++i){
if(donors[i].contribution >= 10000){
grandpatrons_exist = true;
cout << donors[i].name << 'n';
cout << donors[i].contribution << 'n';
}
}
if(!grandpatrons_exist){
cout << "Nonen";
}
cout << "Here's the list of Patrons:n";
for(int i = 0; 1 < amount; ++i){
if(donors[i].contribution < 10000){
cout << donors[i].name << 'n';
cout << donors[i].contribution << 'n';
}
}
delete[] donors;
return 0;
}

现在，更好的解决方案是使用向量而不是原始指针并实现operator>>和operator<<这将大大简化 对象的读取和打印。

#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;
class Donor{
public:
Donor() noexcept: name(), contribution(0){}
friend istream& operator>>(istream& stream, Donor& donor){
switch(stream.peek()){
case  EOF: return stream;
case 'n': stream.ignore();
}
getline(stream, donor.name);
stream >> donor.contribution;
return stream;
}
friend ostream& operator<<(ostream& stream, const Donor& donor){
stream << donor.name << ' ' << donor.contribution;
return stream;
}
const string& get_name() const noexcept{
return name;
}
const double& get_contribution() const noexcept{
return contribution;
}
private:
string name;
double contribution;
};
int main(){
cout << "Enter the filename: ";
string filename;
cin >> filename;
ifstream inFile(filename);
if(!inFile){
cout << "Could not open the file " << filename << 'n';
cout << "Program terminating.n";
exit(EXIT_FAILURE);
}
int amount;
inFile >> amount;
vector<Donor> donors(amount);
//Read it as `for donor in donors`
for(Donor& donor : donors){
inFile >> donor;
}
//An STL function that takes a lambda as the thirs argument. You should read up on them if you haven't.
//I would prefer using this since it greatly improves readability.
//This isn't mandatory, your implementation of this part is good enough.
bool grandpatrons_exist = any_of(begin(donors), end(donors), [](const Donor& donor){ return donor.get_contribution() >= 10000; });
cout << "Here's the list of Grand Patrons:n";
if(grandpatrons_exist){
for(const Donor& donor : donors){
if(donor.get_contribution() >= 10000){
cout << donor << 'n';
}
}   
}
else{
cout << "Nonen";
}
cout << "nHere's the list of Patrons:n";
for(const Donor& donor : donors){
if(donor.get_contribution() < 10000){
cout << donor << 'n';
}
}
return 0;
}

其他一些重大改进将是：

• 使用partition将伟大的赞助人与普通赞助人区分开来。
• 使用流迭代器将对象读入向量。

int main(){
cout << "Enter the filename: ";
string filename;
cin >> filename;
ifstream inFile(filename);
if(!inFile){
cout << "Could not open the file " << filename << 'n';
cout << "Program terminating.n";
exit(EXIT_FAILURE);
}
//Ignore the first line completely
inFile.ignore(numeric_limits<streamsize>::max(), 'n'); 
//Calls `operator>>` internally
vector<Donor> donors(istream_iterator<Donor>{inFile}, istream_iterator<Donor>{});
auto first_grand_patron = partition(begin(donors), end(donors), [](const Donor& donor){ return donor.get_contribution() >= 10000; });
cout << "Here's the list of Grand Patrons:n";
if(first_grand_patron == begin(donors)){
cout << "None!n";
}
for(auto patron = begin(donors); patron != first_grand_patron; ++patron){
cout << *patron << 'n';
}
cout << "nHere's the list of Patrons:n";
for(auto patron = first_grand_patron; patron != end(donors); ++patron){
cout << *patron << 'n';
}
return 0;
}

现在一些一般提示：

• 结构/类名称应以大写字母开头。
• 停止使用 std：：endl。
• 无需cin.clear().Cin 只使用一次，再也不会使用。
• 使用成员初始值设定项列表。
• (可选(在循环中使用++i而不是i++for，以习惯递增变量的正确方法，除非另有需要。
• bool grandpatrons对于标志来说太抽象了。
• donors是一个主观上比捐赠者名单的缩写更好的名称。