c++ - gcc 编译器错误 : STL_construct. h，STL_uninitialized.h

Question

我创建了两个类(class)(学生和类(class)):

#include <iostream>
#include <vector>
#include <string>
#include <stdexcept>
#include <algorithm>
#include <cmath>
#include <list>
using namespace std;




class Student{
    private:
    string name;
    int matr_num;
    int test_1;
    int test_2;

    public:
    //Constructor:
    Student(string name,int matr_num,int test_1,int test_2);
    //Destructor:
    ~Student();
    //Copy constructor:
    Student(const Student& other);
    //Copy assingment:
    Student operator=(const Student& other);
    //Move constructor:
    Student(Student&& other);
    //Move assingment:
    Student operator=(Student&&other);  
    //Average of two tests:
    double test_average();
    //get name,matrikel_number, scores of test:
    string get_name() const ;
    double get_matr_num() const;
    double get_test_1() const ;
    double get_test_2() const ;

};

//Constructor
Student::Student(string name,int matr_num,int test_1,int test_2)
    :name{name},matr_num{matr_num},test_1{test_1},test_2{test_2}
        {
        }

//Destructor
Student::~Student(){
}

//Copy constructor:
Student::Student(const Student& other)
    :name{other.name},matr_num{other.matr_num},test_1{other.test_1},test_2{other.test_2}
        {

        }


//Copy assingment:
Student Student::operator=(const Student& other)
{
    name = other.name;
    matr_num = other.matr_num;
    test_1 = other.test_1;
    test_2 = other.test_2;

}   


//Move Constructor:
Student::Student(Student&& other)
    :name{other.name},matr_num{other.matr_num},test_1{other.test_1},test_2{other.test_2}
        {
            other.name = "";
            other.matr_num = 0;
            other.test_1 = 0;
            other.test_2 = 0;
        }       

//Move assingment:
Student Student::operator=(Student&& other)
{
    name = other.name;
    matr_num = other.matr_num;
    test_1 = other.test_1;
    test_2 = other.test_2;
    other.name = "";
    other.matr_num = 0;
    other.test_1 = 0;
    other.test_2 = 0;
}   

double Student::test_average(){
    return (test_1 + test_2)/2;
}


string Student::get_name()const{return name;}
double Student::get_matr_num()const{return matr_num;}
double Student::get_test_1()const{return test_1;}
double Student::get_test_2()const{return test_2;}


//Course class:
class Course{
private:
    string titel;
    vector<Student> stud_list;

public:
    //Default Constructor:
    Course(string titel);
    //Constructor:
    Course(string titel,vector<Student> students);
    //Destructor:
    ~Course(){};
    //Copy constructor:
    Course(const Course& other);
    //Copy assingment:
    Course operator=(const Course& other);
    //Move constructor:
    Course(Course&& other);
    //Move assingment:
    Course operator=(Course&&other);    
    //average if course for test_1:
    double ave_test_1(){
        double result = 0;
        for(int i = 0; i<stud_list.size();++i){
            result += stud_list[i].get_test_1();
        }
        return result/stud_list.size();
    }

    double ave_test_2(){
        double result = 0;
        for(int i = 0; i<stud_list.size();++i){
            result += stud_list[i].get_test_2();
        }
        return result/stud_list.size();
    }

    double average(){
        double result = 0;
        for(int i = 0; i<stud_list.size();++i){
            result += stud_list[i].test_average();
        }
        return result/stud_list.size();
    }

};


//Default constructor:
Course::Course(string titel)
    : titel{titel}, stud_list{0}{}


//Constructor:
Course::Course(string titel,vector<Student> students){
    titel = titel;
    for(int i = 0;i<students.size();++i){
        stud_list[i] = students[i];
    }
}

//Copy constructor:
Course::Course(const Course& other)
    : titel{other.titel},stud_list{other.stud_list} {}

//Copy assingment:
Course Course::operator=(const Course& other){
    titel = other.titel;
    stud_list = other.stud_list;
}






int main(){
    Student first("Ro Fi", 0123,90,95);
    Student second("Mat Dam",0111,80,87);
    Student third("Mike Ross",0222, 75, 85);

    cout<<first.get_test_1();
}

但是在编译过程中我遇到了以下错误:

n file included from /usr/include/c++/7/vector:62:0,
                 from main.cpp:3:
/usr/include/c++/7/bits/stl_construct.h: In instantiation of ‘void std::_Construct(_T1*, _Args&& ...) [with _T1 = Student; _Args = {}]’:
/usr/include/c++/7/bits/stl_uninitialized.h:527:18:   required from ‘static _ForwardIterator std::__uninitialized_default_n_1<_TrivialValueType>::__uninit_default_n(_ForwardIterator, _Size) [with _ForwardIterator = Student*; _Size = long unsigned int; bool _TrivialValueType = false]’
/usr/include/c++/7/bits/stl_uninitialized.h:583:20:   required from ‘_ForwardIterator std::__uninitialized_default_n(_ForwardIterator, _Size) [with _ForwardIterator = Student*; _Size = long unsigned int]’
/usr/include/c++/7/bits/stl_uninitialized.h:645:44:   required from ‘_ForwardIterator std::__uninitialized_default_n_a(_ForwardIterator, _Size, std::allocator<_Tp>&) [with _ForwardIterator = Student*; _Size = long unsigned int; _Tp = Student]’
/usr/include/c++/7/bits/stl_vector.h:1347:36:   required from ‘void std::vector<_Tp, _Alloc>::_M_default_initialize(std::vector<_Tp, _Alloc>::size_type) [with _Tp = Student; _Alloc = std::allocator<Student>; std::vector<_Tp, _Alloc>::size_type = long unsigned int]’
/usr/include/c++/7/bits/stl_vector.h:285:30:   required from ‘std::vector<_Tp, _Alloc>::vector(std::vector<_Tp, _Alloc>::size_type, const allocator_type&) [with _Tp = Student; _Alloc = std::allocator<Student>; std::vector<_Tp, _Alloc>::size_type = long unsigned int; std::vector<_Tp, _Alloc>::allocator_type = std::allocator<Student>]’
main.cpp:158:29:   required from here
/usr/include/c++/7/bits/stl_construct.h:75:7: error: no matching function for call to ‘Student::Student()’
     { ::new(static_cast<void*>(__p)) _T1(std::forward<_Args>(__args)...); }
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
main.cpp:74:1: note: candidate: Student::Student(Student&&)
 Student::Student(Student&& other)
 ^~~~~~~
main.cpp:74:1: note:   candidate expects 1 argument, 0 provided
main.cpp:55:1: note: candidate: Student::Student(const Student&)
 Student::Student(const Student& other)
 ^~~~~~~
main.cpp:55:1: note:   candidate expects 1 argument, 0 provided
main.cpp:45:1: note: candidate: Student::Student(std::__cxx11::string, int, int, int)
 Student::Student(string name,int matr_num,int test_1,int test_2)
 ^~~~~~~
main.cpp:45:1: note:   candidate expects 4 arguments, 0 provided

我不知道这个错误是什么意思。您能解释一下这里发生了什么以及如何修复它吗？

学生类工作正常，没有任何错误。但是当我添加 Course 类时，我收到了上述错误。那么，这是什么原因呢？

Answer 1

问题出在构造函数中:

Course::Course(string titel)
: titel{titel}
, stud_list{0}{} <--- in here

只需删除 , stud_list{0}{} 。 std::vector<>有一个默认构造函数，可以为您初始化 0 个元素。

您可能还想通过添加 -Wall -Wextra 来编译代码并启用警告。到编译器命令行。