我试图将一天中的一天存储到C ++中的对象中。这本书说它是这样做的，因为C ++没有适当的日期定义，或者至少有一个没有追溯到1970年以后的日子。我一直在努力追随一本书。该脚本以三个输入，月，日和年开始。它通过一个构造函数将它们添加到old参数old，默认为0.
之后我的主程序尝试运行一个函数来计算当天使用pastDays函数的天数，这是个人编写的Date类的一部分，并尝试将其分配给对象中旧的第四个参数。
这里我们有main.cpp / driver程序。构造函数工作，它创建Date类型的对象。
#include <iostream>
#include "Date.h" // Date class definition
#include <time.h>
#include <ctime>
using namespace std;
int main() {
int birthMonth = 0;
int birthDay = 0;
int birthYear = 0;
int dateToMonth = 0;
int dateToDay = 0;
int dateToYear = 0;
cout << "Enter birth month (1-12): ";
cin >> birthMonth;
cout << "Enter birth day (1-31): ";
cin >> birthDay;
cout << "Enter birth year (1900 - 2000): ";
cin >> birthYear;
Date birthDate (birthMonth, birthDay, birthYear);
cout << "To which date would you like to calculate to?\nEnter Day month (1-12): ";
cin >> dateToMonth;
cout << "Enter Day to calculate it to (1-31): ";
cin >> dateToDay;
cout << "Enter Year to calculate it to: ";
cin >> dateToYear;
Date dateTo (dateToMonth, dateToDay, dateToYear);
Date d1( 12, 27, 2010, 0 ); // December 27, 2010
Date d2; // defaults to January 1, 1900
Date::pastDays(birthDate);
Date::pastDays(dateTo);
// birthDate = birthDate - dateTo;
cout << birthDate.old;
}
当我尝试使用它时，... 日期:: pastDays（出生日期）; 我得到错误，“不能在没有对象的情况下调用成员函数'int Date :: pastDays（Date）'。”
我似乎正在通过那里传递物体。
这是Date.h标题。
#ifndef DATE_H
#define DATE_H
#include <array>
#include <iostream>
class Date
{
friend std::ostream &operator<<( std::ostream &, const Date & );
public:
Date( int m = 1, int d = 1, int y = 1900, int o = 0 ); // default constructor
void setDate( int, int, int, int ); // set month, day, year
Date &operator++(); // prefix increment operator
Date operator++( int ); // postfix increment operator
Date &operator+=( unsigned int ); // add days, modify object
int pastDays (Date);
static bool leapYear( int ); // is date in a leap year?
bool endOfMonth( int ) const; // is date at the end of month?
unsigned int month;
unsigned int day;
unsigned int year;
int old;
static const std::array< unsigned int, 13 > days; // days per month
void helpIncrement(); // utility function for incrementing date
}; // end class Date
#endif
这里我们有主要的Date.cpp程序。它首先创建用于复制输入日，月和年的变量。我尝试设计它以便pastDays获取该信息，它将日期和月份减少到1月1日，并将其存储在daysAgo变量中，即创建的负数天数。
然后它会增加年份，并根据它是否是闰年而增加365或366。然后它将当前日期和月份递增回当前日期，将更改添加回daysAgo变量。然后它尝试将其作为entryDay信息，但在旧参数中，以便原始对象现在已填写该信息。至少那是计划。
#include <iostream>
#include <string>
#include "Date.h"
#include <time.h>
#include <ctime>
#include <conio.h>
using namespace std;
// initialize static member; one classwide copy
const array< unsigned int, 13 > Date::days = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
// Date constructor
Date::Date( int month, int day, int year, int old )
{
setDate( month, day, year, old );
} // end Date constructor
// set month, day and year
void Date::setDate( int mm, int dd, int yy, int old )
{
if ( mm >= 1 && mm <= 12 )
month = mm;
else
throw invalid_argument( "Month must be 1-12" );
if ( yy >= 1900 && yy <= 2100 )
year = yy;
// test for a leap year
if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12){
if (dd >= 1 || dd <= 31)
day == dd;
}
if (month == 4 || month == 6 || month == 9 || month == 11){
if (dd >= 1 || dd <= 30)
day == dd;
}
if (month == 2)
if ( year % 4 != 0 ) {
if (dd >= 1 || dd <= 29)
day == dd;
}
if (month == 2)
if ( year % 4 != 0 ) {
if (dd >= 1 || dd <= 28)
day == dd;
}
else {
throw invalid_argument(
"Day is out of range for current month and year" );
}
} // end function setDate
// overloaded prefix increment operator
Date &Date::operator++()
{
helpIncrement(); // increment date
return *this; // reference return to create an lvalue
} // end function operator++
// overloaded postfix increment operator; note that the
// dummy integer parameter does not have a parameter name
Date Date::operator++( int )
{
Date temp = *this; // hold current state of object
helpIncrement();
// return unincremented, saved, temporary object
return temp; // value return; not a reference return
} // end function operator++
// add specified number of days to date
Date &Date::operator+=( unsigned int additionalDays )
{
for ( int i = 0; i < additionalDays; ++i )
helpIncrement();
return *this; // enables cascading
} // end function operator+=
Date pastDays (Date &entryDay) {
//Creating Today date object
time_t t = time(0);
struct tm * now = localtime(&t);
int currentYear = now -> tm_year + 1900;
int currentMonth = now -> tm_mon + 1;
int currentDay = now -> tm_mday;
int birthMonth = entryDay.month;
int birthDay = entryDay.day;
int birthYear = entryDay.year;
//The variable that will be assigned to the old parameter, which can then be subtracted from another time.
int daysAgo = 0;
//Lowering days to 1, to make transition between years easier.
while (birthDay > 1){
birthDay--;
daysAgo--;
}
cout << daysAgo;
//Lowering months to 1, to make transition between years easier.
while (birthMonth > 1){
if (birthMonth == 1 || birthMonth == 3 || birthMonth == 5 || birthMonth == 7 || birthMonth == 8 || birthMonth == 10 || birthMonth == 12){
birthMonth--;
daysAgo -= 31;
}
if (birthMonth == 4 || birthMonth == 6 || birthMonth == 9 || birthMonth == 11){
birthMonth--;
daysAgo -= 30;
}
if (birthMonth == 2)
if ( currentYear % 400 == 0 ||
( currentYear % 100 != 0 && currentYear % 4 == 0 ) ) {
birthMonth--;
daysAgo -= 29;
}
else {
birthMonth--;
daysAgo -= 28;
}
}
cout << daysAgo;
//Incrementing year to current year
while (birthYear < currentYear){
if ( currentYear % 400 == 0 ||
( currentYear % 100 != 0 && currentYear % 4 == 0 ) ) {
daysAgo = daysAgo + 366;
birthYear++;
}
else {
daysAgo = daysAgo + 365;
birthYear++;
}
}
cout << daysAgo;
// Incrementing to current month
while (birthMonth < currentMonth) {
if (birthMonth == 1 || birthMonth == 3 || birthMonth == 5 || birthMonth == 7 || birthMonth == 8 || birthMonth == 10 || birthMonth == 12){
birthMonth++;
daysAgo += 31;
}
if (birthMonth == 4 || birthMonth == 6 || birthMonth == 9 || birthMonth == 11){
birthMonth++;
daysAgo += 30;
}
if (birthMonth == 2)
if ( currentYear % 400 == 0 ||
( currentYear % 100 != 0 && currentYear % 4 == 0 ) ) {
birthMonth++;
daysAgo += 29;
}
else {
birthMonth++;
daysAgo += 28;
}
}
cout << daysAgo;
//Incrementing to current day, and adding the days to the daysAgo
while (birthDay < currentDay){
birthDay++;
daysAgo++;
}
cout << daysAgo;
//Assigning DaysAgo to input parameter.old
entryDay.old = daysAgo;
return(entryDay);
}
// if the year is a leap year, return true; otherwise, return false
bool Date::leapYear( int testYear )
{
if ( testYear % 400 == 0 ||
( testYear % 100 != 0 && testYear % 4 == 0 ) )
return true; // a leap year
else
return false; // not a leap year
} // end function leapYear
// determine whether the day is the last day of the month
bool Date::endOfMonth( int testDay ) const
{
if ( month == 2 && leapYear( year ) )
return testDay == 29; // last day of Feb. in leap year
else
return testDay == days[ month ];
} // end function endOfMonth
// function to help increment the date
void Date::helpIncrement()
{
// day is not end of month
if ( !endOfMonth( day ) )
++day; // increment day
else
if ( month < 12 ) // day is end of month and month < 12
{
++month; // increment month
day = 1; // first day of new month
} // end if
else // last day of year
{
++year; // increment year
month = 1; // first month of new year
day = 1; // first day of new month
} // end else
} // end function helpIncrement
// overloaded output operator
ostream &operator<<( ostream &output, const Date &d )
{
static string monthName[ 13 ] = { "", "January", "February",
"March", "April", "May", "June", "July", "August",
"September", "October", "November", "December" };
output << monthName[ d.month ] << ' ' << d.day << ", " << d.year;
return output; // enables cascading
} // end function operator<<
我的主要问题是我无法计算它的前几天，并将其存储在第四个Date参数中。
点 点 点 点 点
经过几个小时后，我现在修改了程序来计算它已经过了多少天。我在这里列出它供其他人看。也许它会帮助别人。
的main.cpp
#include <iostream>
#include <time.h>
#include <ctime>
#include "Date.cpp" // Date class definition
using namespace std;
int main() {
unsigned int birthMonth = 0;
unsigned int birthDay = 0;
unsigned int birthYear = 0;
unsigned int dateToMonth = 0;
unsigned int dateToDay = 0;
unsigned int dateToYear = 0;
cout << "Enter birth month (1-12): ";
cin >> birthMonth;
cout << "Enter birth day (1-31): ";
cin >> birthDay;
cout << "Enter birth year (1900 - 2000): ";
cin >> birthYear;
Date birthDate (birthMonth, birthDay, birthYear);
cout << "To which date would you like to calculate to?\nEnter Day month (1-12): ";
cin >> dateToMonth;
cout << "Enter Day to calculate it to (1-31): ";
cin >> dateToDay;
cout << "Enter Year to calculate it to: ";
cin >> dateToYear;
Date dateTo (dateToMonth, dateToDay, dateToYear);
pastDays(birthDate);
pastDays(dateTo);
cout << "\nHow many days ago is the birth date? " << birthDate.old << endl;
cout << "How many days ago is the secondary date? " << dateTo.old << endl;
}
这是date.h
#ifndef DATE_H
#define DATE_H
#include <array>
#include <iostream>
class Date
{
friend std::ostream &operator<<( std::ostream &, const Date & );
public:
Date( int m = 1, int d = 1, int y = 1900, int o = 0 ); // default constructor
void setDate( int, int, int, int ); // set month, day, year
// friend Date operator - (Date &ob1, Date &ob2);
Date &operator-(); // Modified Line for Assignment
Date &operator-(Date); // Modified Line for Assignment
void pastDays (Date);
static bool leapYear( int ); // is date in a leap year?
unsigned int month;
unsigned int day;
unsigned int year;
int old;
static const std::array< unsigned int, 13 > days; // days per month
}; // end class Date
#endif
这是Date.cpp
#include <iostream>
#include <string>
#include "Date.h"
#include <time.h>
#include <ctime>
#include <conio.h>
#include "Date.h" // Date class definition
using namespace std;
// initialize static member; one classwide copy
const array< unsigned int, 13 > Date::days = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
// Date constructor
Date::Date( int month, int day, int year, int old )
{
setDate( month, day, year, old );
} // end Date constructor
// set month, day and year
void Date::setDate( int mm, int dd, int yy, int old )
{
if ( mm >= 1 && mm <= 12 )
month = mm;
else
throw invalid_argument( "Month must be 1-12" );
if ( yy >= 1900 && yy <= 2100 )
year = yy;
// test for a leap year
// if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12){
// if (dd >= 1 || dd <= 31)
// day == dd;
// }
// if (month == 4 || month == 6 || month == 9 || month == 11){
// if (dd >= 1 || dd <= 30)
// day == dd;
// }
// if (month == 2)
// if ( year % 4 != 0 ) {
// if (dd >= 1 || dd <= 29)
// day == dd;
// }
// if (month == 2)
// if ( year % 4 != 0 ) {
// if (dd >= 1 || dd <= 28)
// day == dd;
// }
// else {
// throw invalid_argument(
// "Day is out of range for current month and year" );
// }
if ( ( month == 2 && leapYear( year ) && dd >= 1 && dd <= 29 ) ||
( dd >= 1 && dd <= days[ month ] ) )
day = dd;
else
throw invalid_argument(
"Day is out of range for current month and year" );
} // end function setDate
void pastDays (Date &entryDay) {
//Creating Today date object
time_t t = time(0);
struct tm * now = localtime(&t);
int currentYear = now -> tm_year + 1900;
int currentMonth = now -> tm_mon + 1;
int currentDay = now -> tm_mday;
int birthMonth = entryDay.month;
int birthDay = entryDay.day;
int birthYear = entryDay.year;
//The variable that will be assigned to the old parameter, which can then be subtracted from another time.
int daysAgo = 0;
entryDay.old = 0;
cout << endl;
cout << "First" << daysAgo << endl;
cout << "BirthMonth: " << birthMonth << endl;
cout << "BirthDay: " << birthDay << endl;
cout << "BirthYear: " << birthYear << endl;
//Lowering days to 1, to make transition between years easier.
// while (birthDay > 1){
// birthDay--;
// daysAgo--;
// }
daysAgo = daysAgo - birthDay;
daysAgo++;
birthDay = 1;
cout << endl;
cout << "Second" << daysAgo << endl;
cout << "BirthMonth: " << birthMonth << endl;
cout << "BirthDay: " << birthDay << endl;
cout << "BirthYear: " << birthYear << endl;
//Lowering months to 1, to make transition between years easier.
while (birthMonth > 1){
if (birthMonth == 1 || birthMonth == 3 || birthMonth == 5 || birthMonth == 7 || birthMonth == 8 || birthMonth == 10 || birthMonth == 12){
birthMonth--;
daysAgo -= 31;
}
if (birthMonth == 4 || birthMonth == 6 || birthMonth == 9 || birthMonth == 11){
birthMonth--;
daysAgo -= 30;
}
if (birthMonth == 2)
if ( currentYear % 400 == 0 ||
( currentYear % 100 != 0 && currentYear % 4 == 0 ) ) {
birthMonth--;
daysAgo -= 29;
}
else {
birthMonth--;
daysAgo -= 28;
}
}
cout << endl;
cout << "Third" << daysAgo << endl;
cout << "BirthMonth: " << birthMonth << endl;
cout << "BirthDay: " << birthDay << endl;
cout << "BirthYear: " << birthYear << endl;
//Incrementing year to current year
while (birthYear < currentYear){
if ( currentYear % 400 == 0 ||
( currentYear % 100 != 0 && currentYear % 4 == 0 ) ) {
daysAgo = daysAgo + 366;
birthYear++;
}
else {
daysAgo = daysAgo + 365;
birthYear++;
}
}
cout << endl;
cout << "Fourth" << daysAgo << endl;
cout << "BirthMonth: " << birthMonth << endl;
cout << "BirthDay: " << birthDay << endl;
cout << "BirthYear: " << birthYear << endl;
// Incrementing to current month
while (birthMonth < currentMonth) {
if (birthMonth == 1 || birthMonth == 3 || birthMonth == 5 || birthMonth == 7 || birthMonth == 8 || birthMonth == 10 || birthMonth == 12){
birthMonth++;
daysAgo += 31;
}
if (birthMonth == 4 || birthMonth == 6 || birthMonth == 9 || birthMonth == 11){
birthMonth++;
daysAgo += 30;
}
if (birthMonth == 2)
if ( currentYear % 400 == 0 ||
( currentYear % 100 != 0 && currentYear % 4 == 0 ) ) {
birthMonth++;
daysAgo += 29;
}
else {
birthMonth++;
daysAgo += 28;
}
}
cout << endl;
cout << "Fifth" << daysAgo << endl;
cout << "BirthMonth: " << birthMonth << endl;
cout << "BirthDay: " << birthDay << endl;
cout << "BirthYear: " << birthYear << endl;
//Incrementing to current day, and adding the days to the daysAgo
while (birthDay < currentDay){
birthDay++;
daysAgo++;
}
cout << endl;
cout << "Sixth" << daysAgo << endl;
cout << "BirthMonth: " << birthMonth << endl;
cout << "BirthDay: " << birthDay << endl;
cout << "BirthYear: " << birthYear << endl;
//Assigning DaysAgo to input parameter.old
entryDay.old = daysAgo;
}
Date operator - (Date &date1, Date &date2)
{
Date temp;
temp.old = date1.old - date2.old;
if(temp.old < 0)
{
temp.old = temp.old * -1;
}
return(temp);
}
//Date operator-(Date birthDate)
////friend Distance operator - (Date &birthDate, Date &today)
// {
//// int birthMonth = birthDate.month;
//// int birthDay = birthDate.day;
//// int birthYear = birthDate.year;
//// int birthOld = 0;
//// Date temp (birthDate.month, birthDate.day, birthDate.year, birthDate.old);
//
//// pastDays(today);
//// pastDays(birthDate);
//
//// int currentMonth = today.month;
//// int currentDay = today.day;
//// int currentYear = today.year;
//
//// int date1 = pastDays(today);
//// int date2 = pastDays(birthDate);
// Date temp (birthDate.month, birthDate.day, birthDate.year);
//
//// int month, int day, int year, int old
//// temp.month = this -> month;
//// temp.month = this -> day;
//// temp.month = this -> year;
//// Date temp = *this;
// cout << temp.old;
//
// temp.old = *this -> old - birthDate.old;
// //Here I get "Error: Invalid use of 'this' in non-member function;
//
// return(temp);
//}
bool Date::leapYear( int testYear )
{
if ( testYear % 400 == 0 ||
( testYear % 100 != 0 && testYear % 4 == 0 ) )
return true; // a leap year
else
return false; // not a leap year
} // end function leapYear
// overloaded output operator
ostream &operator<<( ostream &output, const Date &d )
{
static string monthName[ 13 ] = { "", "January", "February",
"March", "April", "May", "June", "July", "August",
"September", "October", "November", "December" };
output << monthName[ d.month ] << ' ' << d.day << ", " << d.year;
return output; // enables cascading
} // end function operator<<
答案 0 :(得分：1)
pastDays()的结构令人困惑和奇怪。
Date::pastDays(birthDate); ---> birthDate.pastDate(birthDate) // Would compile and maybe work.
Change to
Date::pastDays(dateTo); ---> dateTo.pastDate(dateTo) // Would compile and maybe work.
但是，如果您只是将该功能的签名更改为：
，则会更加连贯void pastDays (Date &entryDay);
并且删除最后的return entryDay语句，因为该值已经通过引用传递，因此entryDay将在函数执行后执行。
现在，在您调用该函数的代码片段中，您不再使用范围运算符（：:)了：
Date::pastDays(birthDate); ---> pastDate(birthDate);compile and maybe work.
Change to
Date::pastDays(dateTo); ---> pastDate(dateTo);