Problem of adding values in pair then print them.

allenfanwenyuan · #1 26-Oct-2007, 22:56

Hi, fellows, I had a problem about adding a student's name and a unit name in pair into a linked list,then print out student's names under the certain unit or print out unit names a student enrolled. I was doing my way, but seems dosen't work, anyone can help me or point out where i should amend. I also stuck to how to write a destructor, any ideas?

Here is my header file .h

CPP / C++ / C Code:

#ifndef H_School
#define H_School

using namespace std;

struct students
{
       string StuName;
       string units;
       struct students *next;
} ;

class School
{
      public:
            School();
    
           ~School();
    
           void addStudentUnit(string studentName, string unitName);
    
           void printUnitsOfStudent(string studentName);
    
           void printStudentsOfUnit(string unitName);
           
      private:
              students *first;
              
    
};

#endif

Here is implementation file: school.cpp

CPP / C++ / C Code:

#include<iostream>
#include "school.h"
using namespace std;

School::School()
{
       first=NULL;
        
}

School::~School()
{
                 
                 
}

void School::addStudentUnit(string studentName,string unitName)
{
     students *newStu,*last, *p;
   
  
     newStu=new students;
     
     newStu->StuName=studentName;
     newStu->units=unitName;
     newStu->next=NULL;
   
   if(first==NULL)
   {
                  first=newStu;
                  //last=newStu;
   }
   else
   {
       // find last
       p = first;
       last = first;
       while (p != NULL)
       {
             last = p;
             p = p->next;
       }
                last->next=newStu;
                last=newStu;
   }
                
                  
     
               
}

void School::printUnitsOfStudent(string studentName)
{
     students *current;
     current=first;
     if(current->StuName==studentName)
   
         {
    
                         cout<<current->units<<" ";
                         current=current->next;
         }
         cout<<endl;
     
}

void School::printStudentsOfUnit(string unitName)
{
      students *current;
     current=first;
     if(current->units==unitName)
     {
                         cout<<current->StuName<<" ";
                         current=current->next;
     }
}

and finally, my main program: schoolMain.cpp

CPP / C++ / C Code:

#include <iostream>

#include "school.h"

using namespace std;

string menu();

int main() {
  School school;
  string line = menu();
  while (line != "0") {
    if (line == "1") {
      string studentName, unitName;
      cout << "Type the student name:" << endl;
      getline(cin,studentName);
      cout << "Type the unit name:" << endl;
      getline(cin, unitName);
      school.addStudentUnit(studentName,unitName);
    } else if (line == "2") {
      string studentName;
      cout << "Type the student name:" << endl;
      getline(cin,studentName);
      school.printUnitsOfStudent(studentName);
    } else if (line == "3") {
      string unitName;
      cout << "Type the unit name:" << endl;
      getline(cin,unitName);
      school.printStudentsOfUnit(unitName);
    } // end if
    line = menu();
  } // end while

  system("PAUSE");
  return EXIT_SUCCESS;
}


string menu() {
  string r;

  cout << "0: Exit" << endl;
  cout << "1: Add student/unit pair" << endl;
  cout << "2: Print units of a student" << endl;
  cout << "3: Print students of a unit" << endl;
  cout << "Type the option:" << endl;
  
  getline(cin,r);
  return r;
} // end menu

davekw7x · #2 27-Oct-2007, 08:09

Quote:

Originally Posted by allenfanwenyuan

...I had a problem...

Look, yes look, at the logic of your print functions.

For, example to print all the students for a given unit shouldn't it go something like the following?

Code:


set current list item to front of list
while (current list item is not equal to NULL) {
    if (the unit of the current list item is equal to the unit for which you are printing names) {
        print the name for the current list item
    }
    current list item = next list item
}

And similarly for printing all units of a given student.

Regards,

Dave

allenfanwenyuan · #3 27-Oct-2007, 08:16

yeah ....Dave ..I ve already worked it out like following :

CPP / C++ / C Code:

void School::printUnitsOfStudent(string studentName)
{
     students *current;
     current=first;
     while(current!=NULL)
     {
           if(studentName==current->StuName)
                  {
                    cout<<current->units<<" ";
                  }
               else
                      {
                                            cout<<"No student found with that name";
                      }
           
          current=current->next;
     }
     cout<<endl;
}

but i am facing another problem, is how to print student's names or units name alphabetically in ascending order. I am thinking now .....but anyway ....thanks Dave

WaltP · #4 27-Oct-2007, 13:19

After 37 posts and uncounted edits by the administration, you'd think that by now you'd be able to use CODE tags properly. Is there something about the statement

Quote:

The tagindicator is designed for each language forum. Please replace the value tagindicator with one of the following codes representing the language/markup code you are posting

that you don't understand?

And is

Quote:

Use the Preview Post button before Submitting. You can make sure your post looks the way you want it to look, check spelling, check readability, code is formatted, etc.

not worded for proper understanding?

Kimmo · #5 27-Oct-2007, 14:56

Quote:

Originally Posted by allenfanwenyuan

but i am facing another problem, is how to print student's names or units name alphabetically in ascending order. I am thinking now .....but anyway ....thanks Dave

Probably easiest to copy them to some STL container, like vector, sort that and print them.

Designing a sort yourself is a bit more complicated. Before you begin to design a sort, learn how to insert nodes and how to remove nodes from the list. And some sorting algorithm would help too, probably.

allenfanwenyuan · #6 27-Oct-2007, 17:03

Hi Kimmo,
Can u give me some examples how to copy my code to a STL vector container,then sort and print, cause i have not started to study what STL container is . Cheers !

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Problem of adding values in pair then print them.

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