LNK2019: unresolved external symbol _WinMain@16 referenced in function "int __cdecl invoke_main(void)" (?invoke_main@@YAHXZ)

Question

I'm new to c++ and I just don't get this error on visual studio community. I already tried so many things like changing properties settings. Like configuration Type. Also the Subsystem from Console to Windows Rewriting it. At this point I just really need help. So this is my Header file.

#include <iostream>
#include<string>

using namespace std;
#ifndef University_h
#define University_h

class University
{
public:

    University();

    void setUniversityID(int);
    int getUniversityID();

    void setCourseIdSectId(int, int);
    string getCourseIdSectId();

    void setCredits(int);
    int getCredits();

    void setDaysTime(int, string);
    string getDaysTime();

    void setRoomID(int, int);
    string getRoomID();

    void setMaxallotment(int);
    int getMaxallotment();

    void setCampus(string);
    string getCampus();

    void setCourseInstructor(string);
    string getCourseInstructor();

    void setEnrollStudents(int);
    int getEnrollStudents();

    void setCourseStatus(string);
    string getStatus();

private:
    int universityIDNumber;
    int DeptID;
    int sectID;

    int noOfCredits;
    int days;
    string time;

    int buildingID;
    int roomID;

    int maxEnrollment;
    string courseCampus;
    string courseInstructor;
    int noOfStudentsEnrolled;
    string courseStatus;
};

#endif

And this is my main.cpp

#include "University.h"

University::University()
{
    universityIDNumber = 0;
    DeptID = 0;
    sectID = 0;
    noOfCredits = 0;
    days = 0;
    time = "00:00";
    buildingID = 0;;
    roomID = 0;
    maxEnrollment = 0;
    courseCampus = "unknown";
}

void University::setUniversityID(int ID)
{
    universityIDNumber = ID;
}

int University::getUniversityID()
{
    return universityIDNumber;
}

void University::setCourseIdSectId(int deptId, int sId)
{
    DeptID = deptId;
    sectID = sId;
}

string University::getCourseIdSectId()
{
    return DeptID + " " + sectID;
}

void University::setCredits(int credits)
{
    noOfCredits = credits;
}

int University::getCredits()
{
    return noOfCredits;
}

void University::setDaysTime(int ds, string tm)
{
    days = ds;
    time = tm;
}

string University::getDaysTime()
{
    return days + " " + time;
}

void University::setRoomID(int buildId, int roomid)
{
    buildingID = buildId;
    roomID = roomid;
}

string University::getRoomID()
{
return buildingID + " " + roomID;
}

void University::setMaxallotment(int maxNums)
{
    maxEnrollment = maxNums;
}

int University::getMaxallotment()
{
    return maxEnrollment;
}

void University::setCampus(string campusName)
{
    courseCampus = campusName;
}

string University::getCampus()
{
    return courseCampus;
}

void University::setCourseInstructor(string name)
{
    courseInstructor = name;
}

string University::getCourseInstructor()
{
    return courseInstructor;
}

void University::setEnrollStudents(int enrollment)
{
    noOfStudentsEnrolled = enrollment;
}

int University::getEnrollStudents()
{
    return noOfStudentsEnrolled;
}

void University::setCourseStatus(string status)
{
    courseStatus = status;
}

string University::getStatus()
{
    return courseStatus;
}

Answer 1

Do you remember any lectures (or sections in your text-book) telling you that all C++ programs must have a main function?

Well for Windows GUI programs this is called WinMain instead.

Unless you want a Windows GUI program you should make sure that you create a console type project in Visual Studio, and use the existing templates so Visual Studio creates a main function for you.