How can I add data from a public method into a private member array in the same class?

Question

I'm having trouble storing data read in from the keyboard into a private member array.

When I try to simply add the data using:

std::cin >> array[counter];

I get a long error: pasted here to save space

I'm currently trying to find a way to store the input into a temporary variable and then sending it to the array, but I get the same error.

Header:

template<class Type>
class Department
{
  private:
    const static int MAX = 4;
    typedef std::string sArray[MAX];
    typedef Type tArray[MAX];

    std::string deptName;
    sArray names;
    tArray salary;

    public:
       Department(const std::string & dept);
       bool Add() const;
    ...
    ...
};

Implementation:

template<class Type>
Department<Type> :: Department(const std::string & name)
{...}

template<class Type>
bool Department<Type> :: Add() const
{
  if (IsFull())
    return 0;
  else
  {
    Type tempName;
    Type tempSal;
    std::cout << "\nAdd called\n";
    std::cout << "Enter employee ID:\t"; std::cin >> tempName;
    std::cout << "Enter employee salary:\t"; std::cin>>tempSal;

    //What is the best way to add the data stored in tempName, and tempSal to the arrays in the class

    return 1;
  }
}

Link to MCVE

Answer 1

So, the issue came down to that the Add method was marked as const. The error message

invalid operands to binary expression ('std::istream'
(aka 'basic_istream') and 'const std::string' (aka 'const basic_string'))
std::cout << "Enter employee ID:\t"; std::cin >> employee[counter];

really means that the compiler cannot find any operator>> for std::istream (which is cin) that accepts a const std::string

There are two ways to solve this, which both have their advantages and disadvantages.

• You remove the const from Add. The class members are now allowed to be changed (and the employee[counter] will be a std::string instead as far as Add is concerned).

However, Add can change all of the class members.

or

• you add the mutable keyword to employee:

mutable sArray employee;

this will make sArray allowed to be changed even from const. However, now all const functions can change employee.