Linked Lists, C++

[YoYoMan3000]

Hi guys,

I'm trying to write a program that stores a name, ID number, average test score, and letter grade for up to 20 students. This code here will only store/print one student's information. I can't figure out how to get it to store more than that. Any advice?

#include <iostream>
using namespace std;

struct node
  {  char name[20];		 // Name of up to 20 letters
     int idNum;       
     int avgScore[20];     
	 char grade[20];
     node *nxt;			 // Pointer to next node
  };

node *start_ptr = NULL;
node *current;		 // Used to move along the list
int option = 0;

void add_record()
  {  node *temp, *temp2;   // Temporary pointers
	 //node avgScore;
     // Reserve space for new node and fill it with data
	 int* a = NULL;   // Pointer to int, initialize to nothing.
	 int n;           // Size needed for array
	 cout << "\n\t--------------Student Information---------------\n";
	 cout << "How many test scores this semester? ";
	 cin >> n;        // Read in the size
	 a = new int[n];  // Allocate n ints and save ptr in a.
	 for (int i=0; i<n; i++) 
	 {
		 a[i] = 0;    // Initialize all elements to zero.
	 }
     
	 int m;
	 cout << "How many students in the course? ";
	 cin >> m;
	 temp = new node;
	 for (int k=0; k<m; k++)
	 {
		cout << "Please enter the name of student " << (k+1) << ": ";
		cin >> temp->name;
		cout << "Please enter the ID Number of the student : ";
		cin >> temp->idNum;
		cout << "Please enter student's test scores for the " << n << " tests: ";
		for (int j=0; j<n; j++)
		{
			cout << "\nTest " << (j+1) << ": ";
			cin >> a[j];
			/*for (int p=0; p<j; p++)
			{
				temp->avgScore = (temp->avgScore + a[p]) / p;
			}*/
		}

	 }

     temp->nxt = NULL;

     // Set up link to this node
     if (start_ptr == NULL)
       { start_ptr = temp;
	 current = start_ptr;
       }
     else
       { temp2 = start_ptr;
         // We know this is not NULL - list not empty!
         while (temp2->nxt != NULL)
           {  temp2 = temp2->nxt;
              // Move to next link in chain
           }
         temp2->nxt = temp;
       }
  }

void display_list()
  {  node *temp;
     temp = start_ptr;
     cout << endl;
     if (temp == NULL)
       cout << "List currently empty." << endl;
     else
       { while (temp != NULL)
	   {  // Display details for what temp points to
              cout << "Name : " << temp->name << " ";
              cout << "idNum : " << temp->idNum << " ";
			  cout << "avgScore : " << temp->avgScore;
	      if (temp == current)
		cout << " <-- Current node";
              cout << endl;
	      temp = temp->nxt;

	   }
	 cout << "End of list!" << endl;
       }
  }

void main()
  {  start_ptr = NULL;

     do
	{
	  display_list();
	  cout << endl;
	  cout << "Please select an option : " << endl;
	  
	  cout << "1. Create new record." << endl;
	  cout << "2. Exit the program." << endl;

	  cin >> option;

	  switch (option)
	    {
	      case 1 : add_record(); break;
	    }
	}
     while (option != 2);
  }

I know not all the steps are there for everything, my main concern is how to get it to store/print more than one student. I appreciate any responses.

Thanks!

[hujing]

try the following code,there is a minor error in you code

#include <iostream>
using namespace std;

struct node
{  char name[20];		 // Name of up to 20 letters
int idNum;       
int avgScore[20];     
char grade[20];
node *nxt;			 // Pointer to next node
};

node *start_ptr = NULL;
node *current;		 // Used to move along the list
int option = 0;

void add_record()
{ 
	node *temp, *temp2;   // Temporary pointers
	//node avgScore;
	// Reserve space for new node and fill it with data
	int* a = NULL;   // Pointer to int, initialize to nothing.
	int n;           // Size needed for array
	cout << "\n\t--------------Student Information---------------\n";
	cout << "How many test scores this semester? ";
	cin >> n;        // Read in the size
	a = new int[n];  // Allocate n ints and save ptr in a.
	for (int i=0; i<n; i++) 
	{
		a[i] = 0;    // Initialize all elements to zero.
	}
	
	int m;
	cout << "How many students in the course? ";
	cin >> m;
	
	for (int k=0; k<m; k++)
	{	
		temp = new node;
		cout << "Please enter the name of student " << (k+1) << ": ";
		cin >> temp->name;
		cout << "Please enter the ID Number of the student : ";
		cin >> temp->idNum;
		cout << "Please enter student's test scores for the " << n << " tests: ";
		for (int j=0; j<n; j++)
		{
			cout << "\nTest " << (j+1) << ": ";
			cin >> a[j];
			/*for (int p=0; p<j; p++)
			{
			temp->avgScore = (temp->avgScore + a[p]) / p;
		}*/
		}
		temp->nxt = NULL;
		
		// Set up link to this node
		if (start_ptr == NULL)
		{ start_ptr = temp;
		current = start_ptr;
		}
		else
		{ temp2 = start_ptr;
		// We know this is not NULL - list not empty!
		while (temp2->nxt != NULL)
		{  temp2 = temp2->nxt;
		// Move to next link in chain
		}
		temp2->nxt = temp;
		}
	}
	
	
}

void display_list()
{  
	node *temp;
	temp = start_ptr;
	cout << endl;
	if (temp == NULL)
		cout << "List currently empty." << endl;
	else
	{ while (temp != NULL)
	{  // Display details for what temp points to
		cout << "Name : " << temp->name << " ";
		cout << "idNum : " << temp->idNum << " ";
		cout << "avgScore : " << temp->avgScore;
		if (temp == current)
			cout << " <-- Current node";
		cout << endl;
		temp = temp->nxt;
		
	}
	cout << "End of list!" << endl;
	}
}

void main()
{  
	start_ptr = NULL;
	
	do
	{
		display_list();
		cout << endl;
		cout << "Please select an option : " << endl;
		
		cout << "1. Create new record." << endl;
		cout << "2. Exit the program." << endl;
		
		cin >> option;
		
		switch (option)
		{
		case 1 : add_record(); break;
		}
	}
	while (option != 2);
}

[hujing]

Also,you should know you didn't release the memory.

[YoYoMan3000]

Wow! That works! Thank you so very much. What did you change?