写一个C++程序，在界面要求输入顾客的信息，然后保存到文件，然后可以在运行界面显示货物流量和消费人群的统计

以下是一个简单的 C++ 程序，用于输入顾客信息并将其保存到文件中。该程序还会统计货物流量和消费人群的统计，并在运行界面显示。

#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <map>

using namespace std;

struct Customer {
    string name;
    int age;
    string gender;
    string product;
    double price;
};

void saveToFile(const vector<Customer>& customers, const string& filename) {
    ofstream outFile(filename);
    if (!outFile) {
        cerr << "Error: cannot open file " << filename << endl;
        exit(1);
    }

    for (const auto& customer : customers) {
        outFile << customer.name << ',' << customer.age << ',' << customer.gender << ',' << customer.product << ',' << customer.price << endl;
    }
    outFile.close();
}

void readFromFile(vector<Customer>& customers, const string& filename) {
    ifstream inFile(filename);
    if (!inFile) {
        cerr << "Error: cannot open file " << filename << endl;
        exit(1);
    }

    string line;
    while (getline(inFile, line)) {
        Customer customer;
        size_t pos = line.find(',');
        customer.name = line.substr(0, pos);
        line = line.substr(pos + 1);

        pos = line.find(',');
        customer.age = stoi(line.substr(0, pos));
        line = line.substr(pos + 1);

        pos = line.find(',');
        customer.gender = line.substr(0, pos);
        line = line.substr(pos + 1);

        pos = line.find(',');
        customer.product = line.substr(0, pos);
        line = line.substr(pos + 1);

        customer.price = stod(line);

        customers.push_back(customer);
    }
    inFile.close();
}

void printStatistics(const vector<Customer>& customers) {
    map<string, int> productCount;
    map<string, int> genderCount;
    int totalRevenue = 0;

    for (const auto& customer : customers) {
        productCount[customer.product]++;
        genderCount[customer.gender]++;
        totalRevenue += customer.price;
    }

    cout << "Product statistics:" << endl;
    for (const auto& p : productCount) {
        cout << p.first << ": " << p.second << " customers" << endl;
    }

    cout << "Gender statistics:" << endl;
    for (const auto& g : genderCount) {
        cout << g.first << ": " << g.second << " customers" << endl;
    }

    cout << "Total revenue: $" << totalRevenue << endl;
}

int main() {
    vector<Customer> customers;
    string filename = "customers.txt";

    // Read from file
    readFromFile(customers, filename);

    // Input new customer information
    cout << "Enter customer information (name, age, gender, product, price):" << endl;
    Customer customer;
    getline(cin, customer.name, ',');
    cin >> customer.age;
    cin.ignore();
    getline(cin, customer.gender, ',');
    getline(cin, customer.product, ',');
    cin >> customer.price;
    customers.push_back(customer);

    // Save to file
    saveToFile(customers, filename);

    // Print statistics
    printStatistics(customers);

    return 0;
}

在该程序中，我们定义了一个 `Customer` 结构体，用于存储顾客的信息。`saveToFile` 和 `readFromFile` 函数分别用于将顾客信息保存到文件和从文件中读取顾客信息。`printStatistics` 函数用于统计货物流量和消费人群的统计，并在运行界面显示。

在程序运行时，我们首先从文件中读取已有的顾客信息。然后，我们要求用户输入新的顾客信息，并将其添加到 `customers` 向量中。接着，我们将 `customers` 向量中的所有顾客信息保存到文件中。最后，我们打印货物流量和消费人群的统计信息。