我正在尝试构建一个用C ++存储学生成绩的程序。我在编译时收到以下错误：
Undefined symbols for architecture x86_64: "grade1(Student_records const&)", referenced from:
_main in gradereport-a0007a.o
"compare(Student_records const&, Student_records const&)",
referenced from: _main in gradereport-a0007a.o
"read_info(std::__1::basic_istream<char, std::__1::char_traits<char> >&, Student_records&)",
referenced from: _main in gradereport-a0007a.o
ld: symbol(s) not found for architecture x86_64
我一直（尝试）用来编译的命令：g ++ gradereport.cpp
告诉我，我的read_info，compare和grade1函数有些错误（定义不正确）。但是，我似乎无法找到问题。
从以前的帖子阅读＆＃34;未定义的符号＆＃34;问题，似乎（a）我的函数声明不匹配或（b）我需要编译多个文件＆＃34;同时＆＃34; （因为没有更好的短语）。我很确定它不是（a）。如果（b），我将如何完成这项任务？此外，如果有人有任何基本批评，我很乐意听到。提前谢谢。
这是我的代码：
gradereport.cpp
#include<iostream>
#include<ios>
#include<iomanip>
#include<algorithm>
#include<vector>
#include<stdexcept>
#include "student_records.h"
#include "Grades.h"
using std::cout;
using std::endl;
using std::vector;
using std::cout;
using std::cin;
using std::string;
using std::max;
using std::domain_error;
int main()
{
vector<Student_records> students;
Student_records record;
string::size_type maxlen = 0;
while(read_info(cin, record))
{
maxlen = max(maxlen, record.name.size()); // finds the longest name
students.push_back(record); // enters each record into the vector
}
sort(students.begin(), students.end(), compare);
for(vector<Student_records>::size_type i = 0; i != students.size(); ++i)
{
cout << students[i].name
<< string(maxlen + 1 - students[i].name.size(), ' ');
try
{
double final_grade = grade1(students[i]);
/* need to define grade function:
1) unpack grades;
2) find homework grades;
3) find final grade;
*/
cout << final_grade
}
catch(domain_error e)
{
cout << e.what();
}
cout << endl;
}
return 0;
}
student_records.h
#ifndef GUARD_STUDENT_RECORDS
#define GUARD_STUDENT_RECORDS
#include<iostream>
#include<string>
#include<vector>
struct Student_records
{
std::string name;
double midterm, final;
std::vector<double> homeworks;
};
bool compare(const Student_records&, const Student_records&);
std::istream& read_info(std::istream&, Student_records&);
std::istream& read_homework(std::istream&, std::vector<double>&);
#endif
student_records.cpp
#include "student_records.h"
bool compare(const Student_records& x, const Student_records& y)
{
return x.name < y.name;
}
std::istream& read_info(istream& is, Student_records& s)
{
std::cout << "Enter name, midterm, and final: ";
is >> s.name >> s.midterm >> s.final;
read_homework(std::istream&, std::vector<double>&);
return is;
}
std::istream& read_homework(std::istream& in, std::vector<double>& homework)
{
cout << "Enter homework: ";
if(in)
{
hw.clear()
double x;
while(in >> x)
homework.push_back(x);
in.clear();
}
return in;
}
Grades.h
#ifndef GUARD_GRADES
#define GUARD_GRADES
#include<iostream>
#include<vector>
#include<string>
#include "student_records.h"
double grade1(const Student_records&);
double grade2(double, double, std::vector<double>);
double median(std::vector<double>);
#endif
Grades.cpp
#include<stdexcept>
#include<vector>
#include "grades.h"
#include "Student_records.h"
using std::domain_error;
using std::vector;
double grade2(double midterm, double final, std::vector<double> homework)
{
double final_homework_grade;
final_homework_grade = median(homework);
return .4 * final_homework_grade + .4 * final + .2 * midterm;
}
double median(vector<double> homework)
{
typedef vector<double>::size_type vec_sz;
vec_sz size = homework.size();
if(size == 0)
throw domain_error("student has done no homework");
sort(homework.begin(), homework.end());
return size % 2 == 0 ? ((homework[mid] + homework[mid + 1]) / 2) : homework[mid];
}
double grade1(const Student_records& s) // unpacks grades
{
return grade2(s.midterm, s.final, s.homework);
}
答案 0 :(得分：2)