How to change the member value of a struct object? (C++ struct beginner)

Question

Just beginning to learn about structs, I thought I understood how they work, using the dot operator to access a member of an object, but i clearly don't as the readEmployeeRecord function below doesn't work at all. How should i be doing this? (the code is short and self explantory)

Many thanks for taking the time to further explain structs to me! Naturally I tried google first but i couldn't find an example that inputted data quite the way i wanted and wasn't sure how i should be going about it.

#include <iostream>
#include <iomanip>

using namespace std;

//Employee type
struct Employee{
    float wage;
    char status;
    char dept[4]; //for 3letter department, last position is \0 correct?
};

//function definitions
void readEmpoyeeRecord(Employee staff);
void printEmployeeRecord(Employee staff);

int main(){

    Employee employeeA;
    readEmpoyeeRecord(employeeA);
    printEmployeeRecord(employeeA);
    return 0;
}
void readEmpoyeeRecord(Employee employee){
    cout << "Enter empolyees wage: ";
    cin >> employee.wage;
    cout << "Enter empolyees status (H or S): ";
    cin >> employee.status;
    cout << "Enter empolyees dept (ABC): ";
    cin >> employee.dept;
}
void printEmployeeRecord(Employee staff){
    cout << "Wage:     Status:     Department:" <<endl;
    cout << fixed << setprecision( 2 ) << staff.wage;
}

Solution 1

First, try searching google for "passing parameters by reference and by value".

You'll learn that:

void readEmpoyeeRecord(Employee staff);

passes your variable to the function by value, meaning that a copy of your object is created and used inside the function, so your original object doesn't get modified, but a copy.

To get the desired result, use:

void readEmpoyeeRecord(Employee& staff);

Passing by reference means you pass that exact same object, and not a copy.

Your code will basically work like this:

//create new employee
Employee employeeA;
//call method readEmployeeRecord on a copy of employeeA
readEmpoyeeRecord(employeeA);
//call method printEmployeeRecord on a copy of employeeA
printEmployeeRecord(employeeA);

Solution 2

readEmpoyeeRecord(Employee employee) is copy by value, not reference, so you are loosing your changes.

Use readEmpoyeeRecord(Employee& employee) instead.

Solution 3

Your problem is that in C++, objects are passed by value until you specify otherwise. Thus, in the body of readEmpoyeeRecord you're dealing with a copy of employeeA, not with employeeA itself.

Pass a reference to your readEmpoyeeRecord function. The signature of readEmpoyeeRecord should read:

void readEmpoyeeRecord(Employee &employee)