C++ 无效功能与文件流错误

我正在尝试编写一个代码，该代码获取输入文件并对其进行组织并计算一些值。但是，我的 getName 函数遇到了问题，该函数应该通过使用 get 成员函数来汇总输入文件中的字符（如果读取 -1），从而分配一个名字和姓氏以通过引用参数调用。以下是代码的错误参数：

main.cpp:7:14: error: variable or field 'getName' declared void
main.cpp:7:14: error: 'ifstream' was not declared in this scope
main.cpp:7:24: error: 'shoppingCartInput' was not declared in this scope
main.cpp:7:43: error: 'string' was not declared in this scope
main.cpp:7:51: error: 'firstname' was not declared in this scope
main.cpp:7:62: error: 'string' was not declared in this scope
main.cpp:7:70: error: 'lastname' was not declared in this scope
main.cpp:102:50: error: 'getName' was not declared in this scope

这是代码：

#include <iostream>
#include <string>
#include <fstream>
#include <cstdlib>
#include <cctype>
void getName(ifstream& shoppingCartInput, string& firstname, string& lastname);
using namespace std;
int main()
{
    // declerations
    string infile_name = "";
    string shopper = "";
    string firstname ="";
    string lastname = "";
    int quantity;
    double price = 0.0, leastExpPrice = 0, mostExpPrice = 0;
    string item, leastExpItem, mostExpItem;
    double totalCost = 0.0;
    //1) Open Your File
    cout << "please enter the name of the input file:";
    cin >> infile_name;
    cout << "n";
    ifstream shoppingCartInput;
    ofstream shoppingCartOutput;
    shoppingCartInput.open(infile_name.c_str());
    if(shoppingCartInput.fail( )) {
    cout << "Input file opening failed.n";
    exit(1);
    }
    shoppingCartOutput.open("output_file.dat");
    if(shoppingCartOutput.fail( )) {
        cout << "Output file opening failed.n";
        exit(1);
    }
    //2) Read the first line
    shoppingCartInput >> quantity >> price >> item;
    //printing the line to the console (properly organized)
    shoppingCartOutput.setf(ios::fixed);
    shoppingCartOutput.setf(ios::showpoint);
    shoppingCartOutput.setf(ios::left);
    shoppingCartOutput.width(15);
    shoppingCartOutput << item << " ";
    shoppingCartOutput.setf(ios::right);
    shoppingCartOutput.width(3);
    shoppingCartOutput << quantity << " ";
    shoppingCartOutput.setf(ios::right);
    shoppingCartOutput.width(6);
    shoppingCartOutput.precision(2);
    shoppingCartOutput << price << " ";
    shoppingCartOutput.setf(ios::right);
    shoppingCartOutput.width(7);
    shoppingCartOutput.precision(2);
    shoppingCartOutput << (quantity * price) << endl;
    //set it as the most expensive
    //set it as the least expensive
    leastExpPrice = price;
    leastExpItem = item;
    mostExpPrice = price;
    mostExpItem=item;
    //initialize total cost to get the cost of the first line of data
    totalCost = (quantity * price);
    //3) Read until the end of the file
    while(!(shoppingCartInput.eof())) {
        while(quantity != -1) {
            shoppingCartInput >> quantity >> price >> item;
            //printing the line to the console (properly organized)
            shoppingCartOutput.setf(ios::fixed);
            shoppingCartOutput.unsetf(ios::right);
            shoppingCartOutput.setf(ios::showpoint);
            shoppingCartOutput.setf(ios::left);
            shoppingCartOutput.width(15);
            shoppingCartOutput << item << " ";
            shoppingCartOutput.setf(ios::right);
            shoppingCartOutput.width(3);
            shoppingCartOutput << quantity << " ";
            shoppingCartOutput.setf(ios::right);
            shoppingCartOutput.width(6);
            shoppingCartOutput.precision(2);
            shoppingCartOutput << price << " ";
            shoppingCartOutput.setf(ios::right);
            shoppingCartOutput.width(7);
            shoppingCartOutput.precision(2);
            shoppingCartOutput << (quantity * price) << endl;
            if(price < leastExpPrice) {
                leastExpPrice = price;
                leastExpItem = item;
            }
            if(price > mostExpPrice) {
                mostExpPrice = price;
                mostExpItem=item;
            }
            totalCost += (quantity * price);
        }
        if (quantity == (-1)) {
            string first = "";
            string last = "";
            getName(shoppingCartInput, firstname, lastname);
            shopper = firstname + " " + lastname;
            shoppingCartOutput << "ncheapest item = " << leastExpItem <<
                        endl;
            shoppingCartOutput << "most expensive item = " << mostExpIte <<
                        endl;
            shoppingCartOutput << "total cost = " << totalCost << endl;
            shoppingCartOutput.unsetf(ios::right);
            shoppingCartOutput.setf(ios::left);
            shoppingCartOutput << "shopper = " << shopper;
        }
    }
    shoppingCartInput.close();
    shoppingCartOutput.close();
    return 0;
}
void getName(ifstream& shoppingCartInput, std::string& firstname, std::string&
lastname)
{
    char letter;
    do {
         shoppingCartInput.get(letter);
         firstname += letter - 1;
    } while (letter != ',');
    do {
        shoppingCartInput.get(letter);
        lastname += letter;
    } while (letter != 'n' || letter != 'r');
}