Is there a way for a program to generate the name of an instance of a class?

Alright, I did some reading and I think I'm starting to understand how to use references to get around global variables.

Code:

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void addNewEntry(std::vector<db_entry>& data)
{
    data.push_back(db_entry());
    cin >> data.back().value1 >> data.back().value2 >> data.back().value3;
}

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This piece uses the & to make the argument a reference to the vector, so when I call the function I should use something like addNewEntry(data).. or what arguments exactly? I get that anywhere in the program I can go data[7].value1 to get to the value.. and I'm assuming references don't require a -> in place of a . like pointers do?

The reason I thought a pointer was a global variable is cause when I wrote that I didn't understand it was going to be in function arguments and return values.

I don't really use globals that much anyway, but without references in functions like that I wasn't sure how they'd have to be used at least a few times.

Yeah that's right. Here's another usage example:

Code:

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#include <iostream>

int main(){
  std::vector<db_entry> database;
  std::cout << "Enter a db entry";
 
  addNewEntry(database);
  std::cout << "you entered an entry with value1 = " << database.back().value1;
}

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Quote:

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so when I call the function I should use something like addNewEntry(data)

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correct (assuming data is a vector containing db_entry items)

Quote:

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and I'm assuming references don't require a -> in place of a . like pointers do?

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Correct (Unless you are dealing with a reference to a pointer :) )

Okay, I've tried writing something, but now I have lots and lots of wonderful errors.

global.h

Code:

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#include <iostream>
#include <cmath>
#include <vector>
#include <ctime>
using namespace std;

int validateMenuInput(int length);

float getSalary(int hours, float pay);
void addNewEntry(std::vector<database>& employee); //Errors are here
float generateIdNumber();

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In here, it says on the line with void addNewEntry() that:
"'database' was not declared in this scope"
"template 1 argument is invalid"
"template 2 argument is invalid"
"ISO C++ forbids declaration of 'employee' with no type"

Looks like it doesn't realize I declare database as a structure later.. How do I make sure the function declaration knows what database is?

main.cpp

Code:

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int main()
{
    srand((unsigned)time(0));
    struct database
    {
        int idNumber;
        int age;
        string name;
        string title;
        int hours;
        int wage;
        int salary;
    };
    std::vector<database> employee; //Errors are here
    addNewEntry(employee);
    cout<<"number: "<<employee[1].number<<"\n";
}

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I tried to sort out the errors that'll go away when addNewEntry() works properly.. That left me with some on the line that declares the vector:
"'main()::database' uses local type 'main()::database'"
"trying to instantiate `template<class _Alloc> class std::allocator'"
"template argument 2 is invalid"
"invalid type in declaration before ';' token"

addNewEntry() function:

Code:

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void addNewEntry(std::vector<database>& employee)
{
    employee.push_back(database());
    employee.back().idNumber = generateIdNumber();
    cout<<"ID Number: "<<employee.back().idNumber;
    cout<<"Enter the employee's name: ";
    cin>>employee.back().name;
    cout<<"Enter the employee's age: ";
    cin>>employee.back().age;
    cout<<"Enter the employee's title: ";
    cin>>employee.back().title;
    cout<<"Enter the employee's wage: ";
    cin>>employee.back().wage;
    cout<<"Enter the employee's weekly hours: ";
    cin>>employee.back().hours;
    employee.back().salary = getSalary(employee.back().hours, employee.back().wage);
    cout<<"Employee's salary: "<<employee.back().salary;
}

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I just included this in case it's important. generateIdNumber() just returns a number between 10001 and 98304, and getSalary() calculates monthly salary with overtime wages for more than 40 hours a week. I doubt they're causing the problem.


Like most errors I'm guessing this is all because of one thing, which I guess is that the program doesn't realize the vector is for database, especially in the declaration for addNewEntry()

Quote:

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Originally Posted by verxintRising

Okay, I've tried writing something, but now I have lots and lots of wonderful errors.

global.h

Code:

---

#include <iostream>
#include <cmath>
#include <vector>
#include <ctime>
using namespace std;

int validateMenuInput(int length);

float getSalary(int hours, float pay);
void addNewEntry(std::vector<database>& employee); //Errors are here
float generateIdNumber();

---

In here, it says on the line with void addNewEntry() that:
"'database' was not declared in this scope"
"template 1 argument is invalid"
"template 2 argument is invalid"
"ISO C++ forbids declaration of 'employee' with no type"

Looks like it doesn't realize I declare database as a structure later.. How do I make sure the function declaration knows what database is?

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Move the struct to your header file before the place you use it.