Где разместить #include и избыточности в коде (файлы заголовков и реализации)

В настоящее время я прохожу Accelerated C ++, и у меня есть небольшая трудность в понимании, где мне обязательно нужно поместить # include (будь то в заголовке и / или исходном файле) и, в основном, излишне ли я.

Буду признателен за все комментарии о том, что я должен изменить, а что нет необходимости. Я чувствую, что я включаю библиотеки несколько раз (например, если в основной программе есть #include, нужно ли мне это включать в любой из других заголовочных / исходных файлов?). Кроме того, если использовать

#include "Student_info.h"

и файл Student_info.cpp включает grade.h, мне все еще нужно включить grade.h в main.cpp или этого достаточно? Я разместил этот код, потому что я думаю, что приложение к конкретному примеру было бы лучшим способом найти в моей голове правильный способ упорядочить эти файлы, а также распространенные ошибки, которые я должен остерегаться

СПИСОК ФАЙЛОВ — я включаю весь код для полноты, но только верхние части и принципы действительно имеют значение

main.cpp

#include<iostream>
#include<string>
#include<ios>
#include<stdexcept>
#include<vector>
#include<algorithm>
#include<iomanip>
#include "grade.h"#include "Student_info.h"#include "analysis.h"using std::cin;           using std::setprecision;
using std::cout;          using std::sort;
using std::domain_error;  using std::streamsize;
using std::endl;          using std::string;
using std::max;           using std::vector;

int main()
{
//students who did and didn't do their homework
vector<Student_info> did, didnt;

//read the student records and partition them
Student_info student;
while (read(cin,student))
{
if (did_all_hw(student))
did.push_back(student);
else
didnt.push_back(student);

}

//verify that the analyses will show us something
if (did.empty())
{
cout<<"No student did all the homework!"<<endl;
return 1;

}
if (didnt.empty())
{
cout<<"Every student did all the homework!"<<endl;
return 1;
}

//do the analyses
write_analysis(cout, "median",median_analysis, did, didnt);
write_analysis(cout, "average",average_analysis, did, didnt);
write_analysis(cout, "median of homework turned in", optimistic_median_analysis, did, didnt);

return 0;
}

grade.h

#ifndef GUARD_grade_h
#define GUARD_grade_h

//grade.h - Header file
#include<vector>
#include "Student_info.h"

double grade(double, double, double);
double grade(double, double, const std::vector<double>&);
double grade(const Student_info&);

bool fgrade(const Student_info& s);
bool pgrade(const Student_info& s);

double grade_aux(const Student_info& s);

double average(const std::vector<double>& v);
double average_grade(const Student_info& s);
double optimistic_median(const Student_info& s);

#endif

grade.cpp

#include<stdexcept>
#include<vector>
#include<numeric>
#include "grade.h"#include "median.h"#include "Student_info.h"
using std::domain_error;
using std::vector;//reference to constant vector of type double
//vector<double> homework
//vector<double>& hw = homework; (this means that hw is a synonym for homework)
//This function is a ALSO called grade
//This is OVERLOADING and the argument list will be checked to decide which function to call
//The & asks the implementation NOT to copy its argument and const means don't change it
double grade(double midterm, double final, const vector<double>& hw)
{
if (hw.size()==0)
throw domain_error("student has done no homework");
return grade(midterm,final,median(hw));

}

double grade(double midterm, double final, double homework)
{
return 0.2*midterm+0.4*final+0.4*homework;
}//because it's a reference variable, there is no overboard in copying the object
//and modifying it in the function modifies the original variable passed in
//returns double representing OVERALL GRADE
double grade(const Student_info& s)
{
return grade(s.midterm,s.final,s.homework);
}

bool fgrade(const Student_info& s)
{
return grade(s) < 60;
}

bool pgrade(const Student_info& s)
{
return !fgrade(s);
}

//need this function because the transform function can't use grade as there are too many overloaded versions
//and it doesn't know which one to call
double grade_aux(const Student_info& s)
{
try {
return grade(s);
}
catch (domain_error)
{
return grade(s.midterm, s.final, 0);
}
}

//Write the average function to use for average_analysis
double average(const vector<double>& v)
{
//accumulate is defined in the <numeric> library
//The accumulate function adds the values in range denoted by the first two arguments, starting with the
//the value given by the third argument (which also gives the resulting type, e.g. 0.0 will make accumulate return a double
return accumulate(v.begin(),v.end(),0.0)/v.size();
}

double average_grade(const Student_info& s)
{
return grade(s.midterm,s.final, average(s.homework));
}double optimistic_median(const Student_info& s)
{
vector<double> nonzero;
//extracts nonzero vectors from the homework vector and appends them to  (vector<double> nonzero)
remove_copy(s.homework.begin(), s.homework.end(),
back_inserter(nonzero),0);

if (nonzero.empty())
return grade(s.midterm,s.final,0);
else
return grade(s.midterm, s.final,median(nonzero));
}

analysis.h

#ifndef GUARD_output_analysis
#define GUARD_output_analysis
//output_analysis.h - header file
#include<iostream>
#include<vector>
#include<iterator>
#include "Student_info.h"#include "grade.h"#include "median.h"

using std::ostream; using std::string;void write_analysis(ostream& out,
const string& name,
double analysis(const vector<Student_info>&),
const vector<Student_info>& did,
const vector<Student_info>& didnt);double median_analysis(const vector<Student_info>& students);
double average_analysis(const vector<Student_info>& students);
double optimistic_median_analysis(const vector<Student_info>& students);#endif

analysis.cpp

#include<iterator>
#include<algorithm>
#include "Student_info.h"#include "grade.h"#include "median.h"
using std::istream; using std::vector;
using std::ostream; using std::string;
using std::endl;    using std::transform;void write_analysis(ostream& out,
const string& name,
double analysis(const vector<Student_info>&),
const vector<Student_info>& did,
const vector<Student_info>& didnt)
{
out <<name <<" : median(did) = "<<analysis(did)
<<", median(didnt) = "<<analysis(didnt)<<endl;

}

double median_analysis(const vector<Student_info>& students)
{
vector<double> grades;

//The function grade is applied to every element in the range students.begin() to students.end()
//and this is appended to the end of the grades vector
transform(students.begin(), students.end(), back_inserter(grades), grade_aux);

return median(grades);
}

double average_analysis(const vector<Student_info>& students)
{
vector<double> grades;

//recall that tranform applies the average_grade function to every element between students.begin() and students.end()
//and appends this to the end of the grade vector (which is where the iterator returned by back_inserter(grades) points to
transform(students.begin(), students.end(),
back_inserter(grades), average_grade);

return median(grades);
}

double optimistic_median_analysis(const vector<Student_info>& students)
{
vector<double> grades;

transform(students.begin(),students.end(), back_inserter(grades),optimistic_median);

return median(grades);

}

median.h

#ifndef GUARD_median_h
#define GUARD_median_h

//median.h
#include<vector>
double median(std::vector<double>);

#endif

median.cpp

#include "median.h"
using std::vector;
using std::sort;
using std::domain_error;

double median(vector<double> vec)
{
typedef vector<double>::size_type vec_sz;

vec_sz size=vec.size();

//if the vector is empty, an exception is thrown
//execution stops and passes to another part of the program
//along with the exception object
if (size==0)
throw domain_error("median of an empty vector");

sort(vec.begin(),vec.end());

vec_sz mid = size/2;
return size%2==0 ? ((vec[mid]+vec[mid-1])/2) : (vec[mid]);

}

Student_info.h

#ifndef GUARD_Student_info
#define GUARD_Student_info

//Student_info.h header file

#include<iostream>
#include<string>
#include<vector>

using std::vector;struct Student_info {
std::string name;
double midterm,final;
std::vector<double> homework;
};

bool compare(const Student_info&, const Student_info&);
bool did_all_hw(const Student_info& s);

bool pgrade(const Student_info& s);
std::istream& read(std::istream&, Student_info&);
std::istream& read_hw(std::istream&, std::vector<double>&);

vector<Student_info> extract_fails(vector<Student_info>& students);#endif

Student_info.cpp

//Source file for Student_info related functions
#include "Student_info.h"#include "grade.h"
using std::istream; using std::vector;

bool compare(const Student_info& x, const Student_info& y)
{
return x.name < y.name;
}

istream& read(istream& is, Student_info& s)
{
//read and store the student's name and midterm and final exam grades
is >> s.name >> s.midterm >> s.final;

read_hw(is, s.homework); //read AND store all the student's homework grades
return is;

}

istream& read_hw(istream& in, vector<double>& hw)
{
if (in) {

//remove previous contents and leaves us with an empty vector
hw.clear();

double x;
while (in>>x)
hw.push_back(x);

//clear the stream so that input will work for the next student
//reset any error indicatiosn so that input can continue
in.clear();
}

//this means we were given an object that we're NOT going to a copy and we will
//return the object without copying it

return in;
}bool did_all_hw(const Student_info& s)
{
//recall  that if 0 is not found in the sequence given by the first two iterators, then the 2nd argument is returned
return ((find(s.homework.begin(), s.homework.end(), 0)) == s.homework.end());

}

//ONE-PASS SOLUTION
vector<Student_info> extract_fails(vector<Student_info>& students)
{
vector<Student_info>::iterator iter=stable_partition(students.begin(),students.end(),pgrade);
vector<Student_info> fail(iter,students.end()); //vector consisting of all failing elements

students.erase(iter,students.end());
return fail;
}