c++ - 按姓氏对列表进行排序

Question

杰森奇美拉 SE 7039990101

Mike Knuble SSE 7039990102

卡尔·阿尔兹纳 JSE 7039990202

Tom Poti SE 7039990203

Alex Ovechkin 临时股东大会 7039990001

我正在尝试从文件中读取上述信息并按姓氏对其进行排序。我该如何解决这个错误:

错误:需要一个“:”

对于我在 EmployeeInformation 类中声明的字符串？

 class EmployeeInformation {
  public string firstName;
  public string lastName;
  public string title;
  public string phonenumber;

EmployeeInformation(&firstName, &lastName, &title, &phonenumber)
{
    this->firstName = firstName;
    this->lastName = lastName;
    this->initials = title;
    this->id = phoneumber;
}
};


 #include <vector>
 #include <algorithm>
 #include <iostream>
 #include <fstream>

 using namespace std;

int main(int argc, char**argv) {

ifstream file;
file.open("employees.txt");

if (!file.is_open())
    cout << "Error opening file";

vector<EmployeeInformation> employees;
while (!file.eof())
{

    string firstName, lastName, title, phonenumber;
    file >> firstName >> lastName >> title >> phonenumber;
    EmployeeInformation person(firstName, lastName, title, phonenumber);
    employees.push_back(person);
    // end file
}
sort(employees.begin(), employees.end(), [](EmployeeInformation a, EmployeeInformation b) { return a.lastName < b.lastName });

for (EmployeeInformation i : employees)
    // print person info in sorted order

return 0;

Answer 1

很多小错误。

公共(public)部分。

在 C++ 中，public 后跟“:”来标记一个部分。您还需要包含 string 定义。它位于 std:: 命名空间中。

  public: std::string firstName;
  public: std::string lastName;
  public: std::string title;
  public: std::string phonenumber;

C++ 对类型非常迂腐。

您需要指定所有参数的类型:

EmployeeInformation(string const& firstName, string const & lastName, string const& title, string const& phonenumber)

未知名称:

this->initials = title;
  //  ^^^^^^^^   Not a member of this class. Did you mean title.
this->id = phoneumber;
  //  ^^         Not a member of this class. Did you mean phoneumber

语句以';'结束

return a.lastName < b.lastName
                       //      ^^^^^   missing here.

一旦你修复了这些问题，它就会编译。但我会把固定版本带到code review以获得更详细的分解。

当所有完整的 main 看起来像这样时:

int main(int argc, char**argv)
{
    std::ifstream file("employees.txt");

    // Read data into vector
    std::vector<EmployeeInformation> employees(std::istream_iterator<EmployeeInformation>(file),
                                               (std::istream_iterator<EmployeeInformation>()));

    // Sort container.
    std::sort(std::begin(employees), std::end(employees),
              [](EmployeeInformation const& lhs, EmployeeInformation const& rhs) { return lhs.lastName < rhs.lastName;});

    // Copy container to stream.
    std::copy(std::begin(employees), std::end(employees),
              std::ostream_iterator<EmployeeInformation>(std::cout));
}