# C and C++ sample code to implement the date calculator

• 2020-05-27 06:48:09
• OfStack

Question introduction:

Today suddenly saw a problem it looks quite interesting, share with you one. Given any date to introduce a number of days of the date, finally it is concluded that the dates of the add and subtract after. And give two dates you can draw between the two of them how many days apart. (need to consider a leap year, number of days each month is different, we need to write the date of the one we can use directly adder subtracter) because the time is hasty, I did not write interface, only one of several main function of architecture thought and simple to debug.

Code implementation:

``````
#include<iostream>
#include<Windows.h>
#include<assert.h>
using namespace std;

class Date
{

public:

Date(int year = 1997,int month = 1,int day = 1)
:years(year)
, months(month)
, days(day)
{
assert(IScorrect());
}

Date& operator=(const Date& d)
{
if (this != &d)
{
years = d.years;
months = d.months;
days = d.days;
}
return *this;
}

Date& operator + (int day)
{
while (day > 365)
{
if (ISleapyear() && day > 366)
{
years++;
day = day - 366;
}
else
{
years++;
day = day - 365;
}
}
while (day >= Getmonthsday())
{
// Notice the order problem here ,1 Set the first decreased   add   Finally judge .  It will come out if the order is wrong BUG the .
day = day - Getmonthsday();
months++;
if (months > 12)
{
years++;
months = 1;
}
}

while (day > 0)
{
day = day - 1;
days++;
}
return *this;
}

Date& operator - (int day) // Minus the first 1 Year, and then in the use of plus overload , So you just have to write 1 A perfect addition algorithm is enough .
{
while (day > 365)
{
if (ISleapyear() && day > 366)
{
day = day - 366;
years--;
}
else
{
day = day - 365;
years--;
}
}
if (ISleapyear())
{
day = 366 - day;
years--;
}
else
{
day = 365 - day;
years--;
}
operator+(day);
return *this;
}

void DateAdvance() // Used in situations where evolution is possible
{
if (days > Getmonthsday())
{
months++;
days = 1;
}
if (months > 12)
{
years++;
months = 1;
}
}

int operator - (Date D)
{
int count = 0;
if (*this > D)
{
while (*this != D)
{
D.operator+(1);
count++;
}
}
else
{
while (*this != D)
{
operator+(1);
count++;
}
}
return count;
}

bool ISleapyear()
{
if ((years % 4 == 0 && years % 100 != 0) || (years % 400 == 0))
{
return true;
}
return false;
}
int Getmonthsday()
{
int monthDays = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
if (ISleapyear() && months == 2)
{
return 29;
}
return monthDays[months];
}

void print()
{
cout << " The current time is ";
cout << years << "." << months << "." <<days<< endl;
}

bool IScorrect()
{
if (years > 0 && ((years % 4 == 0 && years % 100 != 0) || (years % 400 == 0)) && days < 367)// A leap year
{
if (months >0 && months < 13)
{
if (days > 0 && days <= Getmonthsday())
{
return true;
}
}
}
else if (years >0 && days < 366) // Not a leap year
{
if (months >0 && months < 13)
{
if (days > 0 && days <= Getmonthsday())
{
return true;
}
}
}
return false;
}

Date operator += (int day)
{
*this = *this + 100;
return *this;
}
Date operator -= (int day)
{
return *this = *this - day;
}
inline Date& operator++()
{
*this += 1;
return *this;
}
inline Date operator++(int)
{
Date tmp(*this);
*this = *this + 1;
return tmp;
}

bool operator == (const Date& d)
{
return (years == d.years&& months == d.months&&days == d.days);
}

bool operator != (const Date& d)
{
return !(*this == d);
}

bool operator >(const Date& d)
{
if (years > d.years ||
(years == d.years&&months > d.months)
|| (years == d.years&&months == d.months && days > d.days))
{
return true;
}
return false;
}

bool operator < (const Date& d)
{
return !(*this > d);
}

bool operator >= (const Date& d)
{
return (*this == d) && (*this > d);
}

bool operator <= (const Date& d)
{
return (*this == d) && (*this < d);
}

private:
int years;
int months;
int days;
};

void Test()
{
Date d1(2012, 4, 5);
Date d2(2013, 4, 5);
d1.print();
/*d1 = d1 - 400;*/
d1.print();
cout << d1 - d2 << endl;
d1.print();
system("pause");
}

``````

Conclusion:

The date class is a very important thing for us to know about object orientation, you have to be at least very good at writing this whole framework yourself very quickly and correctly, and then implementing one function at a time, I can only say it's very important, very important, very important for you to know.

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