Won't compile straight from text!

Hi guys!

Here's one that won't compile out of the box (student file from the text). Can anyone tell me why I'm getting:

Data Structs error LNK2019: unresolved external symbol _main referenced in function _mainCRTStartup

Code:

#include <iostream>
#include <fstream>
#include <cstring>
using namespace std;

class Personal {
public:
    Personal();
    Personal(char*,char*,char*,int,long);
    void writeToFile(fstream&) const;
    void readFromFile(fstream&);
    void readKey();
    int size() const {
        return 9 + nameLen + cityLen + sizeof(year) + sizeof(salary);
    }
    bool operator==(const Personal& pr) const {
        return strcmp(pr.SSN,SSN) == 0;
    }
protected:
    const int nameLen, cityLen;
    char SSN[10], *name, *city;
    int year;
    long salary;
    ostream& writeLegibly(ostream&);
    friend ostream& operator<<(ostream& out, Personal& pr) {
        return pr.writeLegibly(out);
    }
    istream& readFromConsole(istream&);
    friend istream& operator>>(istream& in, Personal& pr) {
        return pr.readFromConsole(in);
    }
};

Personal::Personal() : nameLen(10), cityLen(10) {
    name = new char[nameLen+1];
    city = new char[cityLen+1];
}

Personal::Personal(char ........n, char *n, char *c, int y, long s) :
        nameLen(10), cityLen(10) {
    name = new char[nameLen+1];
    city = new char[cityLen+1];
    strcpy(SSN,ssn);
    strcpy(name,n);
    strcpy(city,c);
    year = y;
    salary = s;
}

		void Personal::writeToFile(fstream& out) const {
    out.write(SSN,9);
    out.write(name,nameLen);
    out.write(city,cityLen);
    out.write(reinterpret_cast<const char*>(&year),sizeof(int));
    out.write(reinterpret_cast<const char*>(&salary),sizeof(int));
}

void Personal::readFromFile(fstream& in) {
    in.read(SSN,9);
    in.read(name,nameLen);
    in.read(city,cityLen);
    in.read(reinterpret_cast<char*>(&year),sizeof(int));
    in.read(reinterpret_cast<char*>(&salary),sizeof(int));
}

void Personal::readKey() {
    char s[80];
    cout << "Enter SSN: ";
    cin.getline(s,80);
    strncpy(SSN,s,9);
}

ostream& Personal::writeLegibly(ostream& out) {
    SSN[9] = name[nameLen] = city[cityLen] = '\0';
    out << "SSN = " << SSN << ", name = " << name
        << ", city = " << city << ", year = " << year
        << ", salary = " << salary;
    return out;
}

istream& Personal::readFromConsole(istream& in) {
    char s[80];
    cout << "SSN: ";
    in.getline(s,80);
    strncpy(SSN,s,9);
		cout<<'['<<SSN<<']';
    cout << "Name: ";
    in.getline(s,80);
    strncpy(name,s,nameLen);
		cout<<'['<<name<<']';
    cout << "City: ";
    in.getline(s,80);
    strncpy(city,s,cityLen);
		cout<<'['<<city<<']';
    cout << "Birthyear: ";
    in >> year;
		cout<<'['<<year<<']';
    cout << "Salary: ";
    in >> salary;
		cout<<'['<<salary<<']';
	cin.ignore();
    return in;
}

the class doesnt have an entry point (int main())

create a 'driver' class that creates a variable of type Personal to test your 'Personal' class.

Technically, the code compiles. It just didn't link because you cannot make a program without a place to start.

Originally Posted by Daved

Technically, the code compiles. It just didn't link because you cannot make a program without a place to start.

Thanks, didn't know that that would give me this particular error message.

-Patrick