Find day of the week for a given date
The problem of finding the day of the week for a given date is a common task in computer programming and mathematics. The goal is to determine which day of the week (e.g. Monday, Tuesday, Wednesday, etc.) a specific date falls on, given the month, day, and year.
There are several ways to find the day of the week for a given date, including the following methods:
Zeller's Congruence:
Zeller's congruence is a mathematical formula that can be used to calculate the day of the week for any date in the Gregorian calendar. The formula is as follows:
h = (q + ((13*(m+1))/5) + K + (K/4) + (J/4) - (2*J)) % 7
Where:
- h is the day of the week (0 = Saturday, 1 = Sunday, 2 = Monday, etc.)
- q is the day of the month
- m is the month (3 = March, 4 = April, ..., 14 = February)
- K is the year of the century (i.e. year % 100)
- J is the zero-based century (i.e. year // 100)
Note that for January and February, you need to add 12 to the month and subtract 1 from the year.
Tomohiko Sakamoto's Algorithm:
The Sakamoto's algorithm is a simpler alternative to Zeller's congruence. The algorithm is as follows:
t = [0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4]
y -= m < 3
dow = (y + y//4 - y//100 + y//400 + t[m-1] + d) % 7
Where:
- dow is the day of the week (0 = Sunday, 1 = Monday, 2 = Tuesday, etc.)
- d is the day of the month
- m is the month (1 = January, 2 = February, ..., 12 = December)
- y is the year
Note that the algorithm assumes the Gregorian calendar, so it may not be accurate for dates before 1582.
Program Solution
// C program for
// Find day of the week for a given date
#include <stdio.h>
void dayName(int year, int month, int day)
{
if (month < 1 || month > 12 || day < 1 || day > 31 || year <= 0)
{
return;
}
// Day names
const char *result[] = {
"Sunday" , "Monday" , "Tuesday" , "Wednesday" ,
"Thursday" , "Friday" , "Saturday"
};
// Month 1 2 3 4 5 6 7 8 9 10 11 12
int m[] = {
0 , 3 , 2 , 5 , 0 , 3 , 5 , 1 , 4 , 6 , 2 , 4
};
// Calculate day of week
int d = (year + year / 4 - year / 100 + year / 400 + m[month - 1] + day) % 7;
// Display given date
printf(" Y:%d M:%d D:%d \n", year, month, day);
// Display calculated result
printf(" Week Day : %s \n", result[d]);
}
int main(int argc, char const *argv[])
{
// Test case
dayName(2020, 11, 15);
dayName(2021, 6, 24);
return 0;
}input
Y:2020 M:11 D:15
Week Day : Sunday
Y:2021 M:6 D:24
Week Day : Thursday/*
Java Program for
Find day of the week for a given date
*/
public class Calculation
{
public void dayName(int year, int month, int day)
{
if (month < 1 || month > 12 || day < 1 || day > 31 || year <= 0)
{
return;
}
// Day names
String[] result = {
"Sunday" , "Monday" , "Tuesday" , "Wednesday" , "Thursday" , "Friday" , "Saturday"
};
// Month
// 1 2 3 4 5 6 7 8 9 10 11 12
int[] m = {
0 , 3 , 2 , 5 , 0 , 3 , 5 , 1 , 4 , 6 , 2 , 4
};
// Calculate day of week
int d = (year + year / 4 - year / 100 + year / 400 + m[month - 1] + day) % 7;
// Display given date
System.out.println(" Y:" + year + " M:" + month + " D:" + day);
// Display calculated result
System.out.println(" Week Day : " + result[d]);
}
public static void main(String[] args)
{
Calculation task = new Calculation();
// Test case
task.dayName(2020, 11, 15);
task.dayName(2021, 6, 24);
}
}input
Y:2020 M:11 D:15
Week Day : Sunday
Y:2021 M:6 D:24
Week Day : Thursday// Include header file
#include <iostream>
using namespace std;
/*
C++ Program for
Find day of the week for a given date
*/
class Calculation
{
public: void dayName(int year, int month, int day)
{
if (month < 1 || month > 12 || day < 1 || day > 31 || year <= 0)
{
return;
}
// Day names
string result[] = {
"Sunday" , "Monday" , "Tuesday" , "Wednesday" ,
"Thursday" , "Friday" , "Saturday"
};
// Month
// 1 2 3 4 5 6 7 8 9 10 11 12
int m[] = {
0 , 3 , 2 , 5 , 0 , 3 , 5 , 1 , 4 , 6 , 2 , 4
};
// Calculate day of week
int d = (year + year / 4 - year / 100 + year / 400 + m[month - 1] + day) % 7;
// Display given date
cout << " Y:" << year << " M:" << month << " D:" << day << endl;
// Display calculated result
cout << " Week Day : " << result[d] << endl;
}
};
int main()
{
Calculation *task = new Calculation();
// Test case
task->dayName(2020, 11, 15);
task->dayName(2021, 6, 24);
return 0;
}input
Y:2020 M:11 D:15
Week Day : Sunday
Y:2021 M:6 D:24
Week Day : Thursday// Include namespace system
using System;
/*
Csharp Program for
Find day of the week for a given date
*/
public class Calculation
{
public void dayName(int year, int month, int day)
{
if (month < 1 || month > 12 || day < 1 || day > 31 || year <= 0)
{
return;
}
// Day names
String[] result = {
"Sunday" , "Monday" , "Tuesday" , "Wednesday" , "Thursday" , "Friday" , "Saturday"
};
// Month
// 1 2 3 4 5 6 7 8 9 10 11 12
int[] m = {
0 , 3 , 2 , 5 , 0 , 3 , 5 , 1 , 4 , 6 , 2 , 4
};
// Calculate day of week
int d = (year + year / 4 - year / 100 + year / 400 + m[month - 1] + day) % 7;
// Display given date
Console.WriteLine(" Y:" + year + " M:" + month + " D:" + day);
// Display calculated result
Console.WriteLine(" Week Day : " + result[d]);
}
public static void Main(String[] args)
{
Calculation task = new Calculation();
// Test case
task.dayName(2020, 11, 15);
task.dayName(2021, 6, 24);
}
}input
Y:2020 M:11 D:15
Week Day : Sunday
Y:2021 M:6 D:24
Week Day : Thursday<?php
/*
Php Program for
Find day of the week for a given date
*/
class Calculation
{
public function dayName($year, $month, $day)
{
if ($month < 1 || $month > 12 || $day < 1 || $day > 31 || $year <= 0)
{
return;
}
// Day names
$result = array("Sunday", "Monday", "Tuesday",
"Wednesday", "Thursday", "Friday", "Saturday");
// Month
// 1 2 3 4 5 6 7 8 9 10 11 12
$m = array(0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4);
// Calculate day of week
$d = ($year + (int)($year / 4) - (int)($year / 100) +
(int)($year / 400) + $m[$month - 1] + $day) % 7;
// Display given date
echo " Y:".$year.
" M:".$month.
" D:".$day.
"\n";
// Display calculated result
echo " Week Day : ".$result[$d].
"\n";
}
}
function main()
{
$task = new Calculation();
// Test case
$task->dayName(2020, 11, 15);
$task->dayName(2021, 6, 24);
}
main();input
Y:2020 M:11 D:15
Week Day : Sunday
Y:2021 M:6 D:24
Week Day : Thursday/*
Node JS Program for
Find day of the week for a given date
*/
class Calculation
{
dayName(year, month, day)
{
if (month < 1 || month > 12 || day < 1 || day > 31 || year <= 0)
{
return;
}
// Day names
var result = ["Sunday", "Monday", "Tuesday",
"Wednesday", "Thursday", "Friday", "Saturday"];
// Month
// 1 2 3 4 5 6 7 8 9 10 11 12
var m = [0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4];
// Calculate day of week
var d = (year + parseInt(year / 4) - parseInt(year / 100) +
parseInt(year / 400) + m[month - 1] + day) % 7;
// Display given date
console.log(" Y:" + year + " M:" + month + " D:" + day);
// Display calculated result
console.log(" Week Day : " + result[d]);
}
}
function main()
{
var task = new Calculation();
// Test case
task.dayName(2020, 11, 15);
task.dayName(2021, 6, 24);
}
main();input
Y:2020 M:11 D:15
Week Day : Sunday
Y:2021 M:6 D:24
Week Day : Thursday# Python 3 Program for
# Find day of the week for a given date
class Calculation :
def dayName(self, year, month, day) :
if (month < 1 or month > 12 or day < 1 or day > 31 or year <= 0) :
return
result = ["Sunday", "Monday", "Tuesday", "Wednesday",
"Thursday", "Friday", "Saturday"]
m = [0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4]
d = (year + int(year / 4) - int(year / 100) +
int(year / 400) + m[month - 1] + day) % 7
# Display given date
print(" Y:", year ," M:", month ," D:", day)
# Display calculated result
print(" Week Day : ", result[d])
def main() :
task = Calculation()
# Test case
task.dayName(2020, 11, 15)
task.dayName(2021, 6, 24)
if __name__ == "__main__": main()input
Y: 2020 M: 11 D: 15
Week Day : Sunday
Y: 2021 M: 6 D: 24
Week Day : Thursday# Ruby Program for
# Find day of the week for a given date
class Calculation
def dayName(year, month, day)
if (month < 1 || month > 12 || day < 1 || day > 31 || year <= 0)
return
end
# Day names
result = ["Sunday", "Monday", "Tuesday",
"Wednesday", "Thursday", "Friday", "Saturday"]
# Month
# 1 2 3 4 5 6 7 8 9 10 11 12
m = [0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4]
# Calculate day of week
d = (year + year / 4 - year / 100 + year / 400 +
m[month - 1] + day) % 7
# Display given date
print(" Y:", year ," M:", month ," D:", day, "\n")
# Display calculated result
print(" Week Day : ", result[d], "\n")
end
end
def main()
task = Calculation.new()
# Test case
task.dayName(2020, 11, 15)
task.dayName(2021, 6, 24)
end
main()input
Y:2020 M:11 D:15
Week Day : Sunday
Y:2021 M:6 D:24
Week Day : Thursday
/*
Scala Program for
Find day of the week for a given date
*/
class Calculation()
{
def dayName(year: Int, month: Int, day: Int): Unit = {
if (month < 1 || month > 12 || day < 1 || day > 31 || year <= 0)
{
return;
}
// Day names
var result: Array[String] = Array("Sunday", "Monday",
"Tuesday", "Wednesday", "Thursday", "Friday", "Saturday");
// Month
// 1 2 3 4 5 6 7 8 9 10 11 12
var m: Array[Int] = Array(0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4);
// Calculate day of week
var d: Int = (year + (year / 4).toInt - (year / 100).toInt +
(year / 400).toInt + m(month - 1) + day) % 7;
// Display given date
println(" Y:" + year + " M:" + month + " D:" + day);
// Display calculated result
println(" Week Day : " + result(d));
}
}
object Main
{
def main(args: Array[String]): Unit = {
var task: Calculation = new Calculation();
// Test case
task.dayName(2020, 11, 15);
task.dayName(2021, 6, 24);
}
}input
Y:2020 M:11 D:15
Week Day : Sunday
Y:2021 M:6 D:24
Week Day : Thursday/*
Swift 4 Program for
Find day of the week for a given date
*/
class Calculation
{
func dayName(_ year: Int, _ month: Int, _ day: Int)
{
if (month < 1 || month > 12 || day < 1 || day > 31 || year <= 0)
{
return;
}
// Day names
let result: [String] = ["Sunday", "Monday", "Tuesday",
"Wednesday", "Thursday", "Friday", "Saturday"];
// Month
// 1 2 3 4 5 6 7 8 9 10 11 12
let m: [Int] = [0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4];
// Calculate day of week
let d: Int = (year + year / 4 - year / 100 + year / 400 +
m[month - 1] + day) % 7;
// Display given date
print(" Y:", year ," M:", month ," D:", day);
// Display calculated result
print(" Week Day : ", result[d]);
}
}
func main()
{
let task: Calculation = Calculation();
// Test case
task.dayName(2020, 11, 15);
task.dayName(2021, 6, 24);
}
main();input
Y: 2020 M: 11 D: 15
Week Day : Sunday
Y: 2021 M: 6 D: 24
Week Day : Thursday/*
Kotlin Program for
Find day of the week for a given date
*/
class Calculation
{
fun dayName(year: Int, month: Int, day: Int): Unit
{
if (month < 1 || month > 12 || day < 1 || day > 31 || year <= 0)
{
return;
}
// Day names
val result: Array < String > = arrayOf("Sunday", "Monday", "Tuesday",
"Wednesday", "Thursday", "Friday",
"Saturday");
// Month
// 1 2 3 4 5 6 7 8 9 10 11 12
val m: Array < Int > = arrayOf(0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4);
// Calculate day of week
val d: Int = (year + year / 4 - year / 100 + year / 400 +
m[month - 1] + day) % 7;
// Display given date
println(" Y:" + year + " M:" + month + " D:" + day);
// Display calculated result
println(" Week Day : " + result[d]);
}
}
fun main(args: Array < String > ): Unit
{
val task: Calculation = Calculation();
// Test case
task.dayName(2020, 11, 15);
task.dayName(2021, 6, 24);
}input
Y:2020 M:11 D:15
Week Day : Sunday
Y:2021 M:6 D:24
Week Day : Thursday
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