[英]Initialization of const data members per constructor member-initializer list, error: no matching function for call
[英]Visual Studio compiler error: a call to a delegating constructor shall be the only member-initializer
我有这个程序(如下),它在 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。 我真的想了解如何在 VS 中进行调试并且遇到了麻烦,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它们? 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 ==========
VS 不喜欢struct Course
中的成员string Course
,因为“Course”是构造函数的隐含名称。 重命名成员或结构名称。
我怀疑您遇到了编译器错误。 GCC 和 Clang 都能正确编译您的代码,但不能正确编译 MSVC 。
但是,修复很简单。 似乎 MSVC 不喜欢与 class 同名的成员。 只需将Course
更改为Name
即可:
struct Course
{
string Name;
int Credit = 0;
int Score = 0;
int Grade = 0;
};
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