What is the program to compute calendar?

Answer 1

#include<iostream>

#include<iomanip>

#include<string>

#include<sstream>

bool is_leap_year (unsigned year) { return !(year%400) (!(year%4) && (year%100)); };

unsigned count_leap_years (unsigned year) { return year/4-year/100+year/400; };

unsigned day_of_year (unsigned y, unsigned m, unsigned d);

unsigned long long count_days (unsigned y, unsigned m, unsigned d) {

return 365ULL * (y-1) + count_leap_years(y-1) + day_of_year (y, m, d);}

// compute day of year (January 1st == day 1)

unsigned day_of_year (unsigned y, unsigned m, unsigned d) {

static int DayOfMonth[] = {0,31,59,90,120,151,181,212,243,273,304,334};

return DayOfMonth[m-1] + d + ((m>2 && is_leap_year(y))? 1 : 0);

}

std::ostream& centre_text (std::ostream& os, std::string& str, size_t width) {

if (str.size()<width) {

unsigned spaces {(width-str.size())/2};

while (spaces-->0) os << ' ';

}

return os << str;

}

std::ostream& calendar(std::ostream& os, unsigned y, unsigned m)

{

using namespace std;

string Month[] {"January", "February", "March",

"April", "May", "June",

"July", "August", "September",

"October", "November", "December"};

string Week {"Su Mo Tu We Th Fr Sa"};

unsigned DayOfMonth[] {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

if (is_leap_year (y)) DayOfMonth[1] = 29;

stringstream ss {}; ss << y; // convert year to string

string s {Month[m-1] + ' ' + ss.str()};

os << endl;

centre_text (os, s, Week.size()) << endl;

os << Week << endl;

unsigned first_day {count_days (y, m, 1) % 7};

for(unsigned i {};i<first_day; ++i)

os << " "; // three spaces

for(unsigned i {first_day}, day {1}; day<=DayOfMonth[m-1]; ++i, ++day) {

os << setw(2) << day << ' ';

if(i%7==6) os << endl;

}

return os << std::endl;

}

int main(void){

unsigned year,month;

std::cout << "Enter the month and year: ";

std::cin >> month >> year;

calendar(std::cout, year, month);

}