C++学习(c++17)——1.3一个小程序(part2.Datebase类)

Database的实现

Database.h

#pragma once
#include<iostream>
#include<vector>
#include"Employee.h"

namespace Records {
	const int kFirstEmployeeNumber = 1000;
	class  Database
	{
	public:
		Employee& addEmployee( std::string firstName, std::string lastName);
		Employee getEmployee( int employeeNumber);
		Employee getEmployee(std::string firstName, std::string lastName);

		void displayAll();
		void displayCurrent();
		void displayFormer();

	private:
		std::vector<Employee> mEmployees;
		int mNextEmployeeNumber = kFirstEmployeeNumber;
	};
}

Database.cpp

#include<iostream>
#include<stdexcept>
#include"Database.h"

namespace Records {
	Employee& Database::addEmployee( std::string firstName,  std::string lastName) {
		Employee theEmployee(firstName, lastName);
		theEmployee.setEmployeeNumber(mNextEmployeeNumber++);//每个数据库对象的这个从1000开始加
		theEmployee.hire();
		mEmployees.push_back(theEmployee);
		return mEmployees[mEmployees.size() - 1];//返回最后一个
	}
	Employee Database::getEmployee(int employeeNumber) {
		for ( auto employee : mEmployees) {
			if (employee.getEmployeeNumber() == employeeNumber) {
				return employee;
			}
		}
		throw std::logic_error("No employee found(number)");
	}
	Employee Database::getEmployee(std::string firstName, std::string lastName) {
		for ( auto employee : mEmployees) {
			if (employee.getFirstName()== firstName && employee.getLastName() == lastName) {
				return employee;
			}
		}
		throw std::logic_error("No employee found(name)");
	}
	void Database::displayAll() {
		for (auto employee : mEmployees) {
			employee.display();
		}
	}
	void Database::displayCurrent() {
		for (auto employee : mEmployees) {
			if (employee.isHired()) employee.display();
		}
	}
	void Database::displayFormer() {
		for (auto employee : mEmployees) {
			if (!employee.isHired()) employee.display();
		}
	}
}

main.cpp

// ConsoleApplication1.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//
#include "Employee.h"
#include <iostream>
#include "Database.h"

using namespace std;
using namespace Records;
int main()
{

  /*  Employee emp("John","Daw");
    emp.setSalary(900);
    emp.setEmployeeNumber(1);
    emp.hire();
    emp.promote(50);
    emp.demote(25);
    emp.display();
    return 0; */
    
    Database myDB;
    Employee emp1 = myDB.addEmployee("Greg", "Wallis");
    emp1.fire();
    Employee& emp2 = myDB.addEmployee("Marc","White");
    emp2.setSalary(10000);

    Employee& emp3 = myDB.addEmployee("John", "Doe");
    emp3.setSalary(1000);
    emp3.promote();

    myDB.displayAll();
    std::cout << std::endl;
    myDB.displayCurrent();
    std::cout << std::endl;
    myDB.displayFormer();
}

一开始Database::addEmployee类型忘记加引用&了，导致后面的fire和setSalary、promote都是对临时对象进行，而不会对myDB里的数据进行操作。