我正在尝试创建一个简单的日期类,但是我的主文件上出现了一个错误:“调用重载的Date()是不明确的。”我不知道为什么因为我认为只要我的构造函数有不同的参数,我就可以了。这是我的代码:
头文件:
#ifndef DATE_H
#define DATE_H
using std::string;
class Date
{
public:
static const int monthsPerYear = 12; // num of months in a yr
Date(int = 1, int = 1, int = 1900); // default constructor
Date(); // uses system time to create object
void print() const; // print date in month/day/year format
~Date(); // provided to confirm destruction order
string getMonth(int month) const; // gets month in text format
private:
int month; // 1 - 12
int day; // 1 - 31
int year; // any year
int checkDay(int) const;
};
#endif
.cpp文件
#include <iostream>
#include <iomanip>
#include <string>
#include <ctime>
#include "Date.h"
using namespace std;
Date::Date()
{
time_t seconds = time(NULL);
struct tm* t = localtime(&seconds);
month = t->tm_mon;
day = t->tm_mday;
year = t->tm_year;
}
Date::Date(int mn, int dy, int yr)
{
if (mn > 0 && mn <= monthsPerYear)
month = mn;
else
{
month = 1; // invalid month set to 1
cout << "Invalid month (" << mn << ") set to 1.\n";
}
year = yr; // could validate yr
day = checkDay(dy); // validate the day
// output Date object to show when its constructor is called
cout << "Date object constructor for date ";
print();
cout << endl;
}
void Date::print() const
{
string str;
cout << month << '/' << day << '/' << year << '\n';
// new code for HW2
cout << setfill('0') << setw(3) << day; // prints in ddd
cout << " " << year << '\n'; // yyyy format
str = getMonth(month);
// prints in month (full word), day, year
cout << str << " " << day << ", " << year << '\n';
}
和我的main.cpp
#include <iostream>
#include "Date.h"
using std::cout;
int main()
{
Date date1(4, 30, 1980);
date1.print();
cout << '\n';
Date date2;
date2.print();
}
答案 0 :(得分:21)
Date(int = 1, int = 1, int = 1900); // default constructor
Date(); // uses system time to create object
这些都是可调用的,没有参数。它不能是默认构造的,因为如何构造对象是不明确的。
老实说,拥有这三个默认参数没有多大意义。我何时指定一个而不指定其他人?
答案 1 :(得分:1)
您应该声明两个构造函数:
Date(int day, int month, int year)
{
this->day = day;
this->month = month;
this->year = year;
}
Date(); // uses system time to create object
{
this->day = 1;
this->month = 1;
this->year = 1900;
}
答案 2 :(得分:0)
Date(int = 1, int = 1, int = 1900); // default constructor
Date(); // uses system time to create object
这样会使你的课程变得不再简单。可读性严重受损,您甚至会遇到错误,您不应该浪费时间。请删除无用的默认参数或第二个构造函数。