C++ 从 .txt 文件数据制作矢量

Question

我正在从事另一个学校项目，其中一部分我需要从 .txt 文件中获取数据并将其转换为混合类型向量......其中包含两个整数和一个字符串。我尝试了各种方法，我将其归结为 .txt 文件的输入位置，并希望将其发送到向量。当我尝试用向量做一些事情时，我的困难就出现了。我的代码段如下（我会解释一下 cmets 的用途）：

bool ReadPeopleFromFile(int argc, char* argv[], vector<Person> &people) {
    Person tmpPrsn;
    int tmpAge;
    string tmpGender;
    int tmpAnualIncome;
    ifstream PeopleFile("dev_people.txt"); // Try to open file
    if (!PeopleFile.is_open()) {
        cout << "Could not open file.\n";
        return true; // indicates error
    }

    cout << "Starting" << endl;
    while (!PeopleFile.eof()) {
        PeopleFile >> tmpAge;
        PeopleFile >> tmpGender;
        PeopleFile >> tmpAnualIncome;
        tmpPrsn.SetData(tmpAge, tmpGender, tmpAnualIncome);
        tmpPrsn.Print();
        people.push_back(tmpPrsn);                                                                  //  Need to look at this!!!
    }
    PeopleFile.close();
    cout << "Finished reading file." << endl;
    return false;
}
//I have a function that gets the user input... I took it out for this post.    
vector<Person> ptntlCstmrs;

// Return people within the given age range.
vector<Person> GetPeopleWithQualifyingCharacteristics(vector<Person> ppl, int AgelowerRange, int AgeupperRange, string DesiredGender, int YIlowerRange, int YIupperRange) {
    unsigned int i = 0;
    unsigned int j = 0;
    unsigned int k = 0;

    vector<Person> pplInRange;
    int age = 0;
    string gender = "";
    int yearlyIncome = 0;
    for (i = 0; i < ppl.size(); ++i) {
        for (j = 0; j < ppl.size(); ++j) {
            for (k = 0; k < ppl.size(); ++k) {
                age = ppl.at(i).GetAge();
                gender = ppl.at(j).GetGender();
                yearlyIncome = ppl.at(k).GetYearlyIncome();
                if ((age >= AgelowerRange) && (age <= AgeupperRange) && (gender == DesiredGender || gender == "Any") && (yearlyIncome >= YIlowerRange) && (yearlyIncome <= YIupperRange)) {
                    ptntlCstmrs.push_back(ppl.at(i));
                }
            }
        } // I know this section is messed up... I can't figure out how to get this part to work. What I'm trying to do is take the input, and filter it based on the user-inputted criteria. Nothing that I have done has worked.
    }
    return pplInRange;
}
int main(int argc, char* argv[]) {
    vector<Person> ptntlCstmrs;
    bool hadError = false;
    int ageLowerRange = 0;
    int ageUpperRange = 0;
    string desiredGender = "";
    int yearlyIncomeLowerRange = 0;
    int yearlyIncomeUpperRange = 0;

    hadError = ReadPeopleFromFile(argc, argv, ptntlCstmrs);
    if (hadError) {
        return 1; // indicates error
    }
    GetUserInput(ageLowerRange, ageUpperRange, desiredGender, yearlyIncomeLowerRange, yearlyIncomeUpperRange);
    ptntlCstmrs = GetPeopleWithQualifyingCharacteristics(ptntlCstmrs, ageLowerRange, ageUpperRange, desiredGender, yearlyIncomeLowerRange, yearlyIncomeUpperRange);
    cout << "\nNumber of potential customers = " << ptntlCstmrs.size() << endl;


}

我包含了一堆这样的东西，以防我的一些参考文献被关闭，但我不这么认为。它还告诉你我在做什么。我想帮助弄清楚如何获得对向量进行实际排序的标准，然后打印出这些向量中有多少将与用户输入的数据一起使用。 提前致谢！

Answer 1

这真的归功于@PaulMcKenzie。上面代码的问题在以下部分：

Return people within the given age range.
vector<Person> GetPeopleWithQualifyingCharacteristics(vector<Person> ppl, int AgelowerRange, int AgeupperRange, string DesiredGender, int YIlowerRange, int YIupperRange) {
unsigned int i = 0;
unsigned int j = 0;
unsigned int k = 0;

vector<Person> pplInRange;
int age = 0;
string gender = "";
int yearlyIncome = 0;
for (i = 0; i < ppl.size(); ++i) {
    for (j = 0; j < ppl.size(); ++j) {
        for (k = 0; k < ppl.size(); ++k) {
            age = ppl.at(i).GetAge();
            gender = ppl.at(j).GetGender();
            yearlyIncome = ppl.at(k).GetYearlyIncome();
            if ((age >= AgelowerRange) && (age <= AgeupperRange) && (gender == DesiredGender || gender == "Any") && (yearlyIncome >= YIlowerRange) && (yearlyIncome <= YIupperRange)) {
                ptntlCstmrs.push_back(ppl.at(i));
            }
        }
    } // I know this section is messed up... I can't figure out how to get this part to work. What I'm trying to do is take the input, and filter it based on the user-inputted criteria. Nothing that I have done has worked.
}
return pplInRange;

需要改成如下：

vector<Person> GetPeopleWithQualifyingCharacteristics(vector<Person> ppl, int Agelow, int Ageup, string DesGen, int YIlow, int YIup) {
    unsigned int i = 0;
    int age = 0;
    string gender = "";
    int yearlyIncome = 0;
    ifstream PeopleFile("dev_people.txt");
    while (PeopleFile >> age >> gender >> yearlyIncome);
    vector<Person> pplInRange;

    for (i = 0; i < ppl.size(); ++i) {
        age = ppl.at(i).GetAge();
        gender = ppl.at(i).GetGender();
        yearlyIncome = ppl.at(i).GetYearlyIncome();
        if ((age >= Agelow) && (age <= Ageup) && (DesGen == gender || DesGen == "Any") && (yearlyIncome >= YIlow) && (yearlyIncome <= YIup)) {
            pplInRange.push_back(ppl.at(i));
        }
    }

    return pplInRange;
}

现在它工作正常。谢谢保罗！

Answer 2

我最初的想法是您没有正确收集用户输入。您将确定Person 对象是否是潜在客户的变量发送到另一个函数。

默认情况下，C++ 通过值传递参数——这意味着当一个参数被传递给一个函数时，该参数的副本会被制作并在整个函数中使用。当函数结束时，编辑的参数将​​被处理掉，所有的更改/编辑都将丢失。如果您想从另一个方法中获取用户输入，并且已经保存了输入，请确保通过 reference 传递您的参数。

通过引用传递本质上告诉机器该特定参数在内存中的位置，并允许程序直接访问该内存块，而不是在执行函数时复制参数。这反过来会对参数进行任何更改永久！

希望这会有所帮助！