[C++] Date class implementation, OJ issues related to date calculation

Article directory

• Date design
• Date calculation related OJ questions
• • HJ73 Calculate date to day conversion
  • KY111 date difference
  • KY222 Print date
  • KY258 date accumulation

In software development, dealing with dates is a common task. In order to easily manipulate dates, we can use the C++ programming language to create a simple date class. In this article, we will introduce how to use C++ to implement a basic date class, including date addition, subtraction, size comparison and other functions.

Design of date class

The following is the basic implementation code of the date class:

#pragma once
#include<iostream>
using namespace std;

class Date {<!-- -->
public:
    // Get the number of days in a certain month of a certain year
    int GetMonthDay(const int year, const int month);
    // Constructor
    Date(int year = 1900, int month = 1, int day = 1);
    // copy constructor
    Date(const Date & d);
    // destructor
    ~Date();
    // print date
    void print()const;
    // Assignment operator overloading
    Date & amp; operator=(const Date & amp; d);
    // + = operator overloading
    Date & amp; operator + =(const int day);
    // + operator overloading
    Date operator + (const int day);
    // -= operator overloading
    Date & operator-=(int day);
    // - operator overloading
    Date operator-(int day);
    // Calculate the difference in days between two dates
    int operator-(const Date & amp; d) const;
    // + + Prefix operator overloading
    Date & operator + + ();
    // + + post operator overloading
    Date operator + + (int);
    // --prefix operator overloading
    Date & operator--();
    // --post operator overloading
    Date operator--(int);
    // Greater than operator overloading
    bool operator>(const Date & amp; d) const;
    //Equal operator overloading
    bool operator==(const Date & amp; d) const;
    // Greater than or equal to operator overloading
    bool operator >= (const Date & amp; d) const;
    // Less than operator overloading
    bool operator < (const Date & amp; d) const;
    // Less than or equal to operator overloading
    bool operator <= (const Date & amp; d) const;
    // Not equal to operator overloading
    bool operator != (const Date & amp; d) const;
    //Address operator overloading
    const Date* operator & amp; () const;
    //Output stream operator overloading
    friend ostream & amp; operator << (ostream & amp; out, const Date & amp; d);
    //Input stream operator overloading
    friend istream & amp; operator >> (istream & amp; in, Date & amp; d);

private:
    int _year; // year
    int _month; // month
    int _day; // day
};

// Get the number of days in a certain month of a certain year
int Date::GetMonthDay(const int year, const int month) {<!-- -->
    int monthDay[13] = {<!-- --> 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
    if (2 == month & amp; & amp; ((year % 4 == 0 & amp; & amp; year % 100 != 0) || (year % 400 == 0))) {<!-- -->
        return 29;
    }
    return monthDay[month];
}

// Constructor
Date::Date(int year, int month, int day) {<!-- -->
    if ((year < 1) || (month < 1) || (month > 12) || (day < 1) || (day > GetMonthDay(year, month))) {<!-- -->
        cout << "Illegal date:" << endl;
    }
    _year = year;
    _month = month;
    _day = day;
}

// copy constructor
Date::Date(const Date & amp; d) {<!-- -->
    _year = d._year;
    _month = d._month;
    _day = d._day;
}

// destructor
Date::~Date() {<!-- -->
    _year = 1900;
    _month = 1;
    _day = 1;
}

// print date
void Date::print()const {<!-- -->
    cout << _year << "/" << _month << "/" << _day << endl;
}

// Assignment operator overloading
Date & amp; Date::operator=(const Date & amp; d) {<!-- -->
    if (this != & amp;d) {<!-- -->
        _day = d._day;
        _month = d._month;
        _year = d._year;
    }
    return *this;
}

// + = operator overloading
Date & Date::operator + =(const int day) {<!-- -->
    _day + = day;
    while (_day > GetMonthDay(_year, _month)) {<!-- -->
        _day -= GetMonthDay(_year, _month);
         + + _month;
        if (_month == 13) {<!-- -->
             + + _year;
            _month = 1;
        }
    }
    return *this;
}

// + operator overloading
Date Date::operator + (const int day) {<!-- -->
    Date tmp(*this);
    tmp + = day;
    return tmp;
}

// -= operator overloading
Date & Date::operator-=(int day) {<!-- -->
    _day -= day;
    while (_day < 0) {<!-- -->
        --_month;
        if (_month == 0) {<!-- -->
            --_year;
            _month = 12;
        }
        _day + = GetMonthDay(_year, _month);
    }
    return *this;
}

// - operator overloading
Date Date::operator-(int day) {<!-- -->
    Date tmp(*this);
    tmp -= day;
    return tmp;
}

// Calculate the difference in days between two dates
int Date::operator-(const Date & amp; d) const {<!-- -->
    Date BigDate = *this;
    Date SmallDate = d;
    if (SmallDate > BigDate) {<!-- -->
        BigDate = d;
        SmallDate = *this;
    }
    int count = 0;
    while (SmallDate != BigDate) {<!-- -->
         + + SmallDate;
         + + count;
    }
    return count;
}

// + + Prefix operator overloading
Date & Date::operator + + () {<!-- -->
    *this + = 1;
    return *this;
}

// + + post operator overloading
Date Date::operator + + (int) {<!-- -->
    Date tmp(*this);
    *this + = 1;
    return tmp;
}

// --prefix operator overloading
Date & Date::operator--() {<!-- -->
    *this -= 1;
    return *this;
}

// --post operator overloading
Date Date::operator--(int) {<!-- -->
    Date tmp(*this);
    *this -= 1;
    return tmp;
}

// Greater than operator overloading
bool Date::operator>(const Date & amp; d) const {<!-- -->
    if (_year > d._year || (_year == d._year & amp; & amp; _month > d._month) || (_year == d._year & amp; & amp; _month == d._month & amp; & amp; _day > d._day)) {<!-- -->
        return true;
    }
    return false;
}

//Equal operator overloading
bool Date::operator==(const Date & amp; d) const {<!-- -->
    return _year == d._year & amp; & amp; _month == d._month & amp; & amp; _day == d._day;
}

// Greater than or equal to operator overloading
bool Date::operator >= (const Date & amp; d) const {<!-- -->
    return (*this > d) || (*this == d);
}

// Less than operator overloading
bool Date::operator < (const Date & amp; d) const {<!-- -->
    return !(*this >= d);
}

// Less than or equal to operator overloading
bool Date::operator <= (const Date & amp; d) const {<!-- -->
    return !(*this > d);
}

// Not equal to operator overloading
bool Date::operator != (const Date & amp; d) const {<!-- -->
    return !(*this == d);
}

//Address operator overloading
const Date* Date::operator & amp; () const {<!-- -->
    return this;
}

//Output stream operator overloading
ostream & amp; operator << (ostream & amp; out, const Date & amp; d) {<!-- -->
    out << d._year << "/" << d._month << "/" << d._day;
    return out;
}

//Input stream operator overloading
istream & amp; operator >> (istream & amp; in, Date & amp; d) {<!-- -->
    in >> d._year;
    in >> d._month;
    in >> d._day;
    return in;
}

The above code implements the basic functions of the date class, including constructors, addition and subtraction operator overloading, comparison operator overloading, input and output stream operator overloading, etc.
Below is the main function used to test the code functionality:

int main() {<!-- -->
    //Create a date object and print it
    Date d1(2023, 11, 13);
    cout << "Date 1:";
    d1.print();

    //Copy constructor test
    Date d2(d1);
    cout << "Date 2 (copy construction):";
    d2.print();

    // Assignment operator overload test
    Date d3 = d1;
    cout << "Date 3 (assignment operator overloaded):";
    d3.print();

    // + = operator overload test
    d1 + = 10;
    cout << "Date 1 (after + = operator overloading):";
    d1.print();

    // + operator overload test
    Date d4 = d2 + 5;
    cout << "Date 4 (+ operator overloaded):";
    d4.print();

    // -= operator overload test
    d2 -= 3;
    cout << "Date 2 (after overloading of -= operator):";
    d2.print();

    // - Operator overload testing
    Date d5 = d3 - 7;
    cout << "Date 5 (-operator overloading):";
    d5.print();

    // - Operator overload testing
    int diff = d5 - d4;
    cout << "The difference in days between date 4 and date 5:" << diff << endl;

    // + + Prefix operator overload test
     + + d1;
    cout << "Date 1 (after + + prefix operator overloading):";
    d1.print();

    // + + post operator overload test
    Date d6 = d2 + + ;
    cout << "Date 6 ( + + post operator overloading): ";
    d6.print();
    cout << "Date 2 (after + + post operator overloading):";
    d2.print();

    // -- Prefix operator overload test
    --d3;
    cout << "Date 3 (-- after prefix operator overloading):";
    d3.print();

    // -- post operator overload test
    Date d7 = d4--;
    cout << "Date 7 (--post operator overloading):";
    d7.print();
    cout << "Date 4 (--after operator overloading):";
    d4.print();

    // Greater than operator overload test
    cout << "Is date 5 greater than date 6?" << (d5 > d6 ? "Yes" : "No") << endl;

    //Equality operator overload test
    cout << "Is date 1 equal to date 2?" << (d1 == d2 ? "Yes" : "No") << endl;

    // Not equal to operator overload test
    cout << "Isn't date 3 equal to date 4?" << (d3 != d4 ? "Yes" : "No") << endl;

    // Output stream operator overload test
    cout << "Output stream operator overload for date 1:" << d1 << endl;

    // Input stream operator overload test
    Date d8;
    cout << "Please enter a date (year, month, day):";
    cin >> d8;
    cout << "The date you entered is:" << d8 << endl;

    return 0;
}

C++ implements a simple date class, including date addition, subtraction, size comparison and other functions. The implementation of the date class can help us process dates more conveniently and improve the readability and maintainability of the code.

OJ questions related to date calculation

HJ73 Calculate date to day conversion

https://www.nowcoder.com/practice/769d45d455fe40b385ba32f97e7bcded?tpId=37 & amp; & amp;tqId=21296 & amp;rp=1 & amp;ru=/activity/oj & amp;qru=/ta/huawei /question-ranking

#include <iostream>
using namespace std;

int main() {<!-- -->
    int month[13] = {<!-- -->0, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334};
    int y, m, d;
    cin >> y >> m >> d;
    int day = d;
    if (2 < m & amp; & amp; ((y % 4 == 0 & amp; & amp; y % 100 != 0) || (y % 400 == 0)))
    {<!-- -->
        day + = 1;
    }
    day + = month[m];
    cout << day << endl;
}

KY111 date difference

https://www.nowcoder.com/practice/ccb7383c76fc48d2bbc27a2a6319631c?tpId=62 & amp; & amp;tqId=29468 & amp;rp=1 & amp;ru=/activity/oj & amp;qru=/ta/sju -kaoyan/question-ranking

#include <iostream>
#include <string>
using namespace std;

// Determine whether it is a leap year
bool isLeapYear(int year)
{<!-- -->
    return (year % 4 == 0 & amp; & amp; year % 100 != 0) || (year % 400 == 0);
}

// Get the number of days in a certain month of a certain year
int getDaysOfMonth(int year, int month)
{<!-- -->
    int daysOfMonth[] = {<!-- -->0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    if (month == 2 & amp; & amp; isLeapYear(year))
    {<!-- -->
        return 29;
    }
    return daysOfMonth[month];
}

// Calculate the number of days from AD 0
int getDaysFromZero(int year, int month, int day)
{<!-- -->
    int days = 0;
    for (int y = 1; y < year; + + y)
    {<!-- -->
        days + = isLeapYear(y) ? 366 : 365;
    }
    for (int m = 1; m < month; + + m)
    {<!-- -->
        days + = getDaysOfMonth(year, m);
    }
    days + = day;
    return days;
}

// Calculate the difference in days between two dates
int getDaysDiff(const string & amp; date1, const string & amp; date2)
{<!-- -->
    int year1, month1, day1, year2, month2, day2;
    sscanf(date1.c_str(), "M--", & amp;year1, & amp;month1, & amp;day1);
    sscanf(date2.c_str(), "M--", & amp;year2, & amp;month2, & amp;day2);

    int days1 = getDaysFromZero(year1, month1, day1);
    int days2 = getDaysFromZero(year2, month2, day2);

    return abs(days2 - days1) + 1;
}

int main()
{<!-- -->
    string date1, date2;
    while (cin >> date1 >> date2)
    {<!-- -->
        int daysDiff = getDaysDiff(date1, date2);
        cout << daysDiff << endl;
    }
    return 0;
}

KY222 print date

https://www.nowcoder.com/practice/b1f7a77416194fd3abd63737cdfcf82b?tpId=69 & amp; & amp;tqId=29669 & amp;rp=1 & amp;ru=/activity/oj & amp;qru=/ta/hust -kaoyan/question-ranking

#include <iostream>
using namespace std;

bool isLeapYear(int year)
{<!-- -->
    return (year % 4 == 0 & amp; & amp; year % 100 != 0) || (year % 400 == 0);
}

int getMonthDay(int year, int month)
{<!-- -->
    int daysOfMonth[] = {<!-- -->0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    if (month == 2 & amp; & amp; isLeapYear(year))
    {<!-- -->
        return 29;
    }
    return daysOfMonth[month];
}

int main() {<!-- -->
    int year, day;
    while (cin >> year >> day) {<!-- -->
        int month = 1;
        while (day > getMonthDay(year, month))
        {<!-- -->
            day -= getMonthDay(year, month);
             + + month;
        }
        printf("M- d- d\
", year, month, day);
    }
}

KY258 date accumulation

https://www.nowcoder.com/practice/eebb2983b7bf40408a1360efb33f9e5d?tpId=40 & amp; & amp;tqId=31013 & amp;rp=1 & amp;ru=/activity/oj & amp;qru=/ta/kaoyan /question-ranking

#include <iostream>
using namespace std;

bool isLeapYear(int year)
{<!-- -->
    return (year % 4 == 0 & amp; & amp; year % 100 != 0) || (year % 400 == 0);
}

int getMonthDay(int year, int month)
{<!-- -->
    int daysOfMonth[] = {<!-- -->0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    if (month == 2 & amp; & amp; isLeapYear(year))
    {<!-- -->
        return 29;
    }
    return daysOfMonth[month];
}
int main() {<!-- -->
    int t, year, month, day, add;
    cin >> t;
    while (t--) {<!-- --> // Note that while handles multiple cases
        cin >> year >> month >> day >> add;
        day + = add;
        while (day > getMonthDay(year, month))
        {<!-- -->
            day -= getMonthDay(year, month);
             + + month;
            if (13 == month)
            {<!-- -->
                month = 1;
                 + + year;
            }
        }
        printf("M- d- d\
", year, month, day);
    }
}