Question

1. Write the functions needed to complete the following program as described in the comments. Use the input file course.txt and change the mark of student number 54812 to 80.

/* File: course.cpp

A student's mark in a certain course is stored as a structure (struct student as defined below) consisting of first and last name, student id and mark in the course.  The functions read() and write() are defined for the structure student.  

Information about a course is stored as a structure (struct course as defined below) consisting of the course instructor, course name, course enrollment and an array of students.  The functions read() and write() are defined for the structure course.

   

The user is allowed to change the marks of students using the function update().

*/

   

#include

#include

#include

using namespace std;

struct student

{

   string first;  // first name

   string last;   // last name

   int id;        // student id number

   float mark;    // mark in course

};

void read(istream& in, student& s);

void write(ostream& out, const student& s);

struct course

{

   string instructor;   // "Crooks", for example

   string name;         // "APSC2613", for example

   int size;            // number of students in the class

   student* classlist;  // array of students in the course

};

   

void read(istream& in, course& c);

void write(ostream& out, const course& c);

int update(course& c, int idnumber, float newmark);

int main(void)

{   

   course c;

   int idnumber;    // student id number         

   float newmark;   // updated mark              

   int found;       // flag indicates idnumber found

   ifstream fin ("course.in");

   ofstream fout ("course.out");

   

   // read course information from the file

   read(fin, c);

   cout << c.size << " marks read\n";

   

   // update the marks

   do

   {

      cout << "\n\nEnter the student id followed by the new mark\n";

      cout << "Enter 0 for student number to quit\n";

      

      cin >> idnumber >> newmark;

        

      if(idnumber)

      {

         found = update(c, idnumber,newmark);

      

         if(!found)

            cout << "\nThat student is not in the list\n";

      }

   }while(idnumber != 0);

   write(fout, c);

   

   system("pause");

   return 0;

}

*** Text file components

Crooks

APSC2613

4

Jack White 101102 86

Jill Green 20093 95

Bob Grey 54812 78

Jean Black 55432 89

Answer 1

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Answer :

Please find the code below::

#include <iostream>
#include <string>
#include <fstream>
using namespace std;
struct student
{
string first;
string last;
int id;
float mark; // first name
// last name
// student id number
// mark in course
};
void read(istream& in, student& s){
in>>s.first>>s.last>>s.id>>s.mark;
}
void write(ostream& out, const student& s){
out<<s.first<<" "<<s.last<<" "<<s.id<<" "<<s.mark<<endl;
}
struct course
{
string instructor;
string name;
int size;
student* classlist; // "Crooks", for example
// "APSC2613", for example
// number of students in the class
// array of students in the course
};
void read(istream& in, course& c){
in>>c.instructor;
in>>c.name;
in>>c.size;
c.classlist = new student[c.size];
for(int i=0;i<c.size;i++){
student s ;
read(in,s);
c.classlist[i] = s;
}
}

void write(ostream& out, const course& c){
out<<c.instructor<<endl;
out<<c.name<<endl;
out<<c.size<<endl;
for(int i=0;i<c.size;i++){
write(out,c.classlist[i]);
}

}
int update(course& c, int idnumber, float newmark){
for(int i=0;i<c.size;i++){
if(idnumber==c.classlist[i].id){
c.classlist[i].mark = newmark;
return 1;
}
}
return 0;
}
int main(void)
{
course c;
int idnumber;
float newmark;
int found; // student id number
// updated mark
// flag indicates idnumber found
ifstream fin ("course.txt");
ofstream fout ("courseOut.txt");
// read course information from the file
read(fin, c);
cout << c.size << " marks read\n";
// update the marks
do
{
cout << "\n\nEnter the student id followed by the new mark\n";
cout << "Enter 0 for student number to quit\n";
cin >> idnumber >> newmark;
if(idnumber)
{
found = update(c, idnumber,newmark);
if(!found)
cout << "\nThat student is not in the list\n";
}
}while(idnumber != 0);
write(fout, c);
fout.close();
return 0;
}

output:

course.txt

Crooks
APSC2613
4
Jack White 101102 86
Jill Green 20093 95
Bob Grey 54812 78
Jean Black 55432 89

courseOut.txt

Crooks
APSC2613
4
Jack White 101102 86
Jill Green 20093 95
Bob Grey 54812 80
Jean Black 55432 89