C++ scoping error
- by Pat Murray
I have the following code:
#include "Student.h"
#include "SortedList.h"
using namespace std;
int main() {
// points to the sorted list object
SortedList *list = new SortedList; //This is line 17
// array to hold 100 student objects
Student create[100];
int num = 100000; // holds different ID numbers
// fills an array with 100 students of various ID numbers
for (Student &x : create) {
x = new Student(num);
num += 100;
}
// insert all students into the sorted list
for (Student &x : create)
list->insert(&x);
delete list;
return 0;
}
And I keep getting the compile time error:
main.cpp: In function ‘int main()’:
main.cpp:17: error: ‘SortedList’ was not declared in this scope
main.cpp:17: error: ‘list’ was not declared in this scope
main.cpp:17: error: expected type-specifier before ‘SortedList’
main.cpp:17: error: expected `;' before ‘SortedList’
main.cpp:20: error: ‘Student’ was not declared in this scope
main.cpp:20: error: expected primary-expression before ‘]’ token
main.cpp:20: error: expected `;' before ‘create’
main.cpp:25: error: expected `;' before ‘x’
main.cpp:31: error: expected primary-expression before ‘for’
main.cpp:31: error: expected `;' before ‘for’
main.cpp:31: error: expected primary-expression before ‘for’
main.cpp:31: error: expected `)' before ‘for’
main.cpp:31: error: expected `;' before ‘x’
main.cpp:34: error: type ‘<type error>’ argument given to ‘delete’, expected pointer
main.cpp:35: error: expected primary-expression before ‘return’
main.cpp:35: error: expected `)' before ‘return’
My Student.cpp and SortedList.cpp files compile just fine. They both also include .h files. I just do not understand why I get an error on that line. It seems to be a small issue though. Any insight would be appreciated.
UPDATE1: I originally had .h files included, but i changed it when trying to figure out the cause of the error. The error remains with the .h files included though.
UPDATE2:
SortedList.h
#ifndef SORTEDLIST_H
#define SORTEDLIST_H
#include "Student.h"
/*
* SortedList class
*
* A SortedList is an ordered collection of Students. The Students are ordered
* from lowest numbered student ID to highest numbered student ID.
*/
class SortedList {
public:
SortedList();
// Constructs an empty list.
SortedList(const SortedList & l);
// Constructs a copy of the given student object
~SortedList();
// Destructs the sorted list object
const SortedList & operator=(const SortedList & l);
// Defines the assignment operator between two sorted list objects
bool insert(Student *s);
// If a student with the same ID is not already in the list, inserts
// the given student into the list in the appropriate place and returns
// true. If there is already a student in the list with the same ID
// then the list is not changed and false is returned.
Student *find(int studentID);
// Searches the list for a student with the given student ID. If the
// student is found, it is returned; if it is not found, NULL is returned.
Student *remove(int studentID);
// Searches the list for a student with the given student ID. If the
// student is found, the student is removed from the list and returned;
// if no student is found with the given ID, NULL is returned.
// Note that the Student is NOT deleted - it is returned - however,
// the removed list node should be deleted.
void print() const;
// Prints out the list of students to standard output. The students are
// printed in order of student ID (from smallest to largest), one per line
private:
// Since Listnodes will only be used within the SortedList class,
// we make it private.
struct Listnode {
Student *student;
Listnode *next;
};
Listnode *head; // pointer to first node in the list
static void freeList(Listnode *L);
// Traverses throught the linked list and deallocates each node
static Listnode *copyList(Listnode *L);
// Returns a pointer to the first node within a particular list
};
#endif
#ifndef STUDENT_H
#define STUDENT_H
Student.h
#ifndef STUDENT_H
#define STUDENT_H
/*
* Student class
*
* A Student object contains a student ID, the number of credits, and an
* overall GPA.
*/
class Student {
public:
Student();
// Constructs a default student with an ID of 0, 0 credits, and 0.0 GPA.
Student(int ID);
// Constructs a student with the given ID, 0 credits, and 0.0 GPA.
Student(int ID, int cr, double grPtAv);
// Constructs a student with the given ID, number of credits, and GPA.\
Student(const Student & s);
// Constructs a copy of another student object
~Student();
// Destructs a student object
const Student & operator=(const Student & rhs);
// Defines the assignment operator between two student objects
// Accessors
int getID() const; // returns the student ID
int getCredits() const; // returns the number of credits
double getGPA() const; // returns the GPA
// Other methods
void update(char grade, int cr);
// Updates the total credits and overall GPA to take into account the
// additions of the given letter grade in a course with the given number
// of credits. The update is done by first converting the letter grade
// into a numeric value (A = 4.0, B = 3.0, etc.). The new GPA is
// calculated using the formula:
//
// (oldGPA * old_total_credits) + (numeric_grade * cr)
// newGPA = ---------------------------------------------------
// old_total_credits + cr
//
// Finally, the total credits is updated (to old_total_credits + cr)
void print() const;
// Prints out the student to standard output in the format:
// ID,credits,GPA
// Note: the end-of-line is NOT printed after the student information
private:
int studentID;
int credits;
double GPA;
};
#endif
