Problem With Random Number Generator

[mysiarobin1987]

I am a college student taking a C++ class, and was given this assignment:
Goal: Write a program that will make use of your knowledge of pointers to build a sorted linked list. The program should include the
following:
1. Create a struct with the following items: name (string), score (int) and grade (char).
2. Create a node and fill it by doing the following:
a. read names from in.dat data file (attached)
b. Generate a score for each node from 0 to 100. This field of the struct should be randomly generated by using the
rand function.
c. Assign a grade to each node as the following: 0-59: F; 60-69: D; 70-79: C; 80-89: B and 90-100: A.
3. Build a linked list of the nodes according to ascending order of score.
4. Print the listing of students/score/grade to the screen in row/column format. There should be proper t so that reader can tell
what each column representing for.

I'm not really having a problem. The function is able to assign a random grade to each student, however when I run the program, it assigns the same grade to each student. How can I make the program assign a different grade to each student?

//main.cpp

#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
#include <time.h> 
#include "P4-linkedList_Elliott.h"

using namespace std;

//Default constructor
linkedList::linkedList()
{
   head = NULL;
} 

//Function to create node
node* linkedList::createNode(string name)
{
   node* newNode = new node;
   newNode->name = name;
   newNode->score = getScore();
   newNode->grade = getGrade(newNode->score);
   return newNode;
}

//Function to get student's letter grade
char linkedList::getGrade(int score)
{
   if (0 <= score && score <= 59)
       return 'F';
   else if (60 <= score && score <= 69)
       return 'D';
   else if (70 <= score && score <= 79)
       return 'C';
   else if (80 <= score && score <= 89)
       return 'B';
   else if (90 <= score && score <=100)
       return 'A';
}

//Function to generate random number for student's number grade
int linkedList::getScore()
{
	time_t secs;

	time(&secs);

	srand((unsigned int) secs);
  
	return rand() % 100+0;
}

//Function to create a line for each student
void linkedList::create(string name)
{
	node* newNode = createNode(name);   
	newNode->next = NULL;

if (head == NULL || head->score >= newNode->score )
	{
		newNode->next = head;
		head = newNode;
		return;
	}
	
else if (head->next != NULL && head->next->score >= newNode->score)
	{
		newNode->next = head->next;
		head->next = newNode;
		return;
	}
	
else
	{
		node * left;
		node * right = head;	
	
while(right != NULL && right->next->score <= newNode->score)
	{
		left = right;
		right = right->next;
	}
		left->next=newNode;
		newNode->next = right;
	}
}
//Function to print the list as a table
void linkedList::print()
{
	node *n = head;
	while (n != NULL)
{
			cout.width(30);
			cout << n->name;
			cout.width(25);
			cout << n->score;
			cout.width(25);
			cout << n->grade << endl;
			n = n->next;  
}
}		

int main()
{
	//Code to read from file
   string line;
   
   ifstream in_file;
   
   linkedList list;
   
   in_file.open( "infile.dat");
   
   while (std::getline(in_file, line))
   {  
       list.create(line); //Function call to create line for each student
   }
   //Header of the table
   			cout.width(30);
   			cout << left;
			cout << "Student Name";
			cout.width(25);
			cout << "Score";
			cout.width(25);
			cout << "Grade" << endl;
   list.print(); //Function call to print the table of student's names and grades
     
   return 0; 
}

// header file
#include<iostream>
using namespace std;

//Definition of the node
struct node
{
	string name; // Variable to hold the student's name
	int score; // Variable to hold the student's number score
	char grade; // Variable to hold the student's letter grade
	node *next; // Declaring pointer *next
};

//Definition of linkedList class to create iterators
//to objects of the linkedList class

class linkedList
{
   private:
       node *head; 
       node* createNode(string name);
       char getGrade(int score);
       int getScore();
   public:
       linkedList();
       void create(string name);
       void print();
  
};

This is what prints on the screen:
Student Name                  Score                    Grade
Woods Marcus                  99                       A
Wilson Delora                 99                       A
Thompson Fernando             99                       A
Smith Devin                   99                       A
Robinson Cordale              99                       A
Ricks Ezra                    99                       A
Price Gerald                  99                       A
Powell Kiara                  99                       A
Nagal Jimmy                   99                       A
Mirador GeoAlbert             99                       A
Longs Chatwaneice             99                       A
Jones Kobe                    99                       A
Johnlouis Ajayla              99                       A
Holley Deyana                 99                       A
Holden Tre                    99                       A
Harris Dontel                 99                       A
Hardy Ashley                  99                       A
Elliott Mysia                 99                       A
Chapman Thomas                99                       A
Carrion Antonio               99                       A
Andrews-Graham D'Kyra         99                       A 

[helios]

You should only call srand() once, at the start of the program.

[dhayden]

You need to seed the random number generator once instead of each time you call rand(). Just move lines 48-50 to line 113.

[dhayden]

mysiarobin1987, my comment should have been to move lines 46-50, not lines 48-50.

Once you fix that, you'll find that linkedList::create() doesn't work. You didn't see this before because you were always inserting at the start of the list. At line 80, right might not be NULL, but right->next might.

But rather than fix it, you should rewrite create(), it's much more complex than necessary. Here is a more traditional way of doing it:

//Function to create a line for each student
void
linkedList::create(string name)
{
    node *newNode = createNode(name);

    node *cur, *prev = NULL;
    for (cur = head; cur; prev = cur, cur = cur->next) {
        if (cur->score >= newNode->score) {
            break;
        }
    }
    newNode->next = cur;
    if (prev) {
        prev->next = newNode;
    } else {
        head = newNode;
    }
}

The better way is to take advantage of the fact that C++ let's you take the address of a variable. Instead of a prev pointer, create a variable that points to head, or cur->next:

//Function to create a line for each student
void
linkedList::create(string name)
{
    node *newNode = createNode(name);

    node **pp, *cur;
    for(pp = &head; (cur = *pp); pp = &(cur->next)) {
        if (cur->score >= newNode->score) {
            break;
        }
    }
    newNode->next = cur;
    *pp = newNode;
}

[mysiarobin1987]

THANK YOU SO MUCH AGAIN!! THAT REALLY HELPED !! @DHAYDEN