c++ - Visual Studio 编译器错误 : a call to a delegating constructor shall be the only member-initializer

Question

我有这个程序(如下)在 Visual Studios 中不断给我一些编译器错误。但是当我用 GCC 运行它时，我没有得到编译错误。我真的很想了解如何在 VS 中进行调试，但遇到了麻烦，因为编译器错误都指向代码的最后一行。谁能帮我弄清楚错误的含义以及如何解决这些错误？我还有一张 VS 给我的错误图片:

#include <iostream>
#include <vector>
#include <fstream>
#include <string>
using namespace std;

struct Course
{
   string Course;
   int Credit = 0;
   int Score = 0;
   int Grade = 0;
};

struct Student

{
   int ID = 0;
   string Name = "";
   // Course arrCourse[maxCourseAmt];
     vector <Course>Courses;

};

int isInStudVector(vector<Student>vect, int target)
{
   int i = 0;
       while (i <= vect.size())
       {
           if (vect[i].ID == target)
               return i;
           i++;
       }
       return -1;

}



int main()
{
   fstream inputFile;
   string  fileName = "StudentRecords.txt";
   string token;
   //Student arrStu[9];
   vector<Student>Students;

   inputFile.open(fileName, ios::in);

   if (inputFile.is_open())

   {
       int index = 0;
       int ID;
       string Name;
       string CourseName;
       int Credit;
       int Score;

       while (!inputFile.eof())

       {

           inputFile >> ID >> Name >> CourseName >> Credit >> Score;

           int ii = isInStudVector(Students, ID);

           if (ii == -1) // The student record does not exist

           {
               Students.push_back(Student());

               Students[index].ID = ID;

               Students[index].Name = Name;
               Students[index].Courses.push_back(Course());
               Students[index].Courses[0].Course = CourseName;
               Students[index].Courses[0].Credit = Credit;
               Students[index].Courses[0].Score = Score;

               index++;

           }

           else /// The student exists

           {
               /// Add course and score to the existing student record
           }
       }
       inputFile.close();

   }

   else

       cout << "File cannot be opened.";

   return 0;

}

Rebuild started...
1>------ Rebuild All started: Project: hw1, Configuration: Debug Win32 ------
1>hw1.cpp
1>C:\Users\Rob\source\repos\hw1\hw1\hw1.cpp(28,14): warning C4018: '<=': signed/unsigned mismatch
1>C:\Users\Rob\source\repos\hw1\hw1\hw1.cpp(105,1): error C3511: 'Course': a call to a delegating constructor shall be the only member-initializer
1>C:\Users\Rob\source\repos\hw1\hw1\hw1.cpp(105,1): message : This diagnostic occurred in the compiler generated function 'Course::Course(Course &&)'
1>C:\Users\Rob\source\repos\hw1\hw1\hw1.cpp(105,1): error C2664: 'Course::Course(const Course &)': cannot convert argument 1 from 'std::string' to 'const Course &'
1>C:\Users\Rob\source\repos\hw1\hw1\hw1.cpp(105,1): message : Reason: cannot convert from 'std::string' to 'const Course'
1>C:\Users\Rob\source\repos\hw1\hw1\hw1.cpp(105,1): message : No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
1>C:\Users\Rob\source\repos\hw1\hw1\hw1.cpp(13,1): message : see declaration of 'Course::Course'
1>C:\Users\Rob\source\repos\hw1\hw1\hw1.cpp(105,1): message : This diagnostic occurred in the compiler generated function 'Course::Course(Course &&)'
1>C:\Users\Rob\source\repos\hw1\hw1\hw1.cpp(105,1): error C2437: 'Credit': has already been initialized
1>C:\Users\Rob\source\repos\hw1\hw1\hw1.cpp(105,1): message : This diagnostic occurred in the compiler generated function 'Course::Course(Course &&)'
1>C:\Users\Rob\source\repos\hw1\hw1\hw1.cpp(105,1): error C2437: 'Score': has already been initialized
1>C:\Users\Rob\source\repos\hw1\hw1\hw1.cpp(105,1): message : This diagnostic occurred in the compiler generated function 'Course::Course(Course &&)'
1>C:\Users\Rob\source\repos\hw1\hw1\hw1.cpp(105,1): error C2437: 'Grade': has already been initialized
1>C:\Users\Rob\source\repos\hw1\hw1\hw1.cpp(105,1): message : This diagnostic occurred in the compiler generated function 'Course::Course(Course &&)'
1>Done building project "hw1.vcxproj" -- FAILED.
========== Rebuild All: 0 succeeded, 1 failed, 0 skipped ==========

Answer 1

我怀疑您遇到了编译器错误。 Both GCC and Clang compiles your code correctly, but not MSVC .

但是，修复很简单。似乎 MSVC 不喜欢与类同名的成员。只需将 Course 更改为 Name 即可解决问题:

struct Course
{
   string Name;
   int Credit = 0;
   int Score = 0;
   int Grade = 0;
};