How to print the marks of 10 students in c plus plus?

Answer 1

#include<iostream>

#include<iomanip>

#include<vector>

#include<string>

#include<random>

#include<time.h>

struct student_t

{

unsigned m_student_id;

std::string m_student_name;

student_t(const unsigned student_id, const std::string& student_name): m_student_id(student_id), m_student_name(student_name) {}

};

struct students_t : std::vector<student_t>

{

students_t() : std::vector<student_t> ()

{

push_back( student_t( 1, "Albert Black"));

push_back( student_t( 2, "Charlie Dawson"));

push_back( student_t( 3, "Eric Farrel"));

push_back( student_t( 4, "Gary Houston"));

push_back( student_t( 5, "Iain Jackson"));

push_back( student_t( 6, "Kevin Lawson"));

push_back( student_t( 7, "Michael Nicholson"));

push_back( student_t( 8, "Oscar Peterson"));

push_back( student_t( 9, "Robert Stevenson"));

push_back( student_t( 10, "Tony Urquart"));

}

};

struct subject_t

{

unsigned m_subject_id;

std::string m_subject_name;

subject_t(const unsigned subject_id, const std::string& subject_name): m_subject_id(subject_id), m_subject_name(subject_name) {}

};

struct subjects_t : std::vector<subject_t>

{

subjects_t() : std::vector<subject_t> ()

{

push_back( subject_t( 1, "English"));

push_back( subject_t( 2, "Mathematics"));

push_back( subject_t( 3, "Physics"));

push_back( subject_t( 4, "Biology"));

push_back( subject_t( 5, "Chemistry"));

push_back( subject_t( 6, "History"));

push_back( subject_t( 7, "Geography"));

}

unsigned max_length()

{

// Returns length of longest name.

unsigned max=0;

for (std::vector<subject_t>::const_iterator isubject=begin(); isubject!=end(); ++isubject)

{

const subject_t& subject = *isubject;

if (max < subject.m_subject_name.size())

max = subject.m_subject_name.size();

}

return max;

}

};

struct mark_t

{

student_t& m_student;

subject_t& m_subject;

unsigned m_mark;

mark_t(student_t& student, subject_t& subject, const unsigned mark): m_student(student), m_subject(subject), m_mark(mark) {}

mark_t& operator= (const mark_t& rvalue)

{

this->m_student = rvalue.m_student;

this->m_subject = rvalue.m_subject;

this->m_mark = rvalue.m_mark;

return *this;

}

};

struct marks_t : std::vector<mark_t>

{

students_t& m_students;

subjects_t& m_subjects;

marks_t (students_t& students, subjects_t& subjects) : std::vector<mark_t>(), m_students(students), m_subjects(subjects)

{

// pseudo-random number generator

std::default_random_engine generator;

generator.seed ((unsigned) time (NULL));

std::uniform_int_distribution<unsigned> distribution (0, 100);

for (std::vector<student_t>::const_iterator istudent=students.begin(); istudent!=students.end(); ++istudent)

{

student_t& student = const_cast<student_t&> (*istudent);

for (std::vector<subject_t>::const_iterator isubject=subjects.begin(); isubject!=subjects.end(); ++isubject)

{

subject_t& subject = const_cast<subject_t&> (*isubject);

push_back( mark_t(student, subject, distribution(generator)));

}

}

}

std::ostream& print (std::ostream& os)

{

unsigned last_student_id = 0;

for (std::vector<mark_t>::const_iterator imark=begin(); imark!=end(); ++imark)

{

const student_t& student = imark->m_student;

if (last_student_id != student.m_student_id)

{

if (last_student_id)

os << '\n';

last_student_id = student.m_student_id;

os << '#' << student.m_student_id << '\t' << student.m_student_name << ":\n" << std::endl;

}

const subject_t& subject = imark->m_subject;

os << '\t' << std::setw (m_subjects.max_length()) << subject.m_subject_name << '\t' << std::setw(3) << imark->m_mark << std::endl;

}

os << std::endl;

return os;

}

};

int main()

{

students_t students;

subjects_t subjects;

marks_t marks (students, subjects);

marks.print (std::cout);

}