0 points

# (Current date and time) Invoking time(0) returns the elapse time in milliseconds since midnight January 1, 1970. Write a program that displays the date and time. Here is a sample run:

Thu Nov 12 2020 06:04:07 GMT+0000 (UTC)

Posted by @mahmoud hussein

```#include <iostream>
#include<cmath>
#include<ctime>
#include<string>
#include <iomanip>
#include <fstream>

using namespace std;

string dayNameOfWeek(int dayOfWeek);
int getMonthFromDays(int year, int days);
int getNumOfDaysToReachThatMonth(int year, int month);
int getStartDay(int year, int month);
int getTotalNumberOfDays(int year, int month);
int getNumberOfDaysInMonth(int year, int month);
bool isLeapYear(int year);
string getMonthName(int month);

int main()
{

// Obtain the total seconds since midnight, Jan 1, 1970
long totalSeconds = time(0);

// Compute the current second in the minute in the hour
long currentSecond = (int)(totalSeconds % 60);

// Obtain the total minutes
long totalMinutes = totalSeconds / 60;

// Compute the current minute in the hour
long currentMinute = (int)(totalMinutes % 60);

// Obtain the total hours
long totalHours = totalMinutes / 60;

// Compute the current hour
long currentHour = (int)(totalHours % 24);

long totalDays = totalHours / 24;

// current year
int currentYear = (int)(totalDays / 365) + 1970;

long daysInCurrentYear = (totalDays - numberOfLeapYearsSince1970(currentYear)) % 365;
if (currentHour > 0) daysInCurrentYear++; // add today

// get current month number
int currentMonthNum = getMonthFromDays(currentYear, (int)daysInCurrentYear);

// getting current month name
string month = getMonthName(currentMonthNum);

// getting day of current month
int daysTillCurrentMonth = getNumOfDaysToReachThatMonth(currentYear, currentMonthNum);

int startDay = getStartDay(currentYear, currentMonthNum);
int today = (int)daysInCurrentYear - daysTillCurrentMonth + 1;
string dayOfWeek = dayNameOfWeek(((startDay + today) % 7));

// Display results
cout<<" Current date and time: " <<dayOfWeek << " " + month << " " << today << ", " <<currentYear
<< " " << currentHour << ":"
<< currentMinute << ":" << currentSecond;

}

string dayNameOfWeek(int dayOfWeek) {

switch (dayOfWeek) {
case 2: return "Monday";
case 3: return "Tuesday";
case 4: return "Wednesday";
case 5: return "Thursday";
case 6: return "Friday";
case 7: return "Saturday";
case 1: return "Sunday";
}
}

int count = 0;
for (int i = 1970; i <= year; i++) {
if (isLeapYear(i))count++;
}
return count;
}

int getMonthFromDays(int year, int days) {
int dayTracker = 0;
for (int i = 1; i <= 12; i++) {

dayTracker += getNumberOfDaysInMonth(year, i);

if (dayTracker > days) return i;
}
return 12;
}

int getNumOfDaysToReachThatMonth(int year, int month) {
int dayTracker = 0;
for (int i = 1; i < month; i++) {

dayTracker += getNumberOfDaysInMonth(year, i);

}
return dayTracker;
}

/** Get the start day of month/1/year */
int getStartDay(int year, int month) {
const int START_DAY_FOR_JAN_1_1800 = 3;
// Get total number of days from 1/1/1800 to month/1/year
int totalNumberOfDays = getTotalNumberOfDays(year, month);

// Return the start day for month/1/year
return (totalNumberOfDays + START_DAY_FOR_JAN_1_1800) % 7;
}

/** Get the total number of days since January 1, 1800 */
int getTotalNumberOfDays(int year, int month) {
int total = 0;

// Get the total days from 1800 to 1/1/year
for (int i = 1800; i < year; i++)
if (isLeapYear(i))
total = total + 366;
else
total = total + 365;

// Add days from Jan to the month prior to the calendar month
for (int i = 1; i < month; i++)
total = total + getNumberOfDaysInMonth(year, i);

}

/** Get the number of days in a month */
int getNumberOfDaysInMonth(int year, int month) {

if (month == 1 || month == 3 || month == 5 || month == 7 ||
month == 8 || month == 10 || month == 12)
return 31;

if (month == 4 || month == 6 || month == 9 || month == 11)
return 30;

if (month == 2) return isLeapYear(year) ? 29 : 28;

return 0; // If month is incorrect
}

/** Determine if it is a leap year */
bool isLeapYear(int year) {
return year % 400 == 0 || (year % 4 == 0 && year % 100 != 0);
}

/** Get the English name for the month 1-12 */
string getMonthName(int month) {
string monthName = "";
switch (month) {
case 1: monthName = "January"; break;
case 2: monthName = "February"; break;
case 3: monthName = "March"; break;
case 4: monthName = "April"; break;
case 5: monthName = "May"; break;
case 6: monthName = "June"; break;
case 7: monthName = "July"; break;
case 8: monthName = "August"; break;
case 9: monthName = "September"; break;
case 10: monthName = "October"; break;
case 11: monthName = "November"; break;
case 12: monthName = "December";
}

return monthName;
}

```
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