Introduction

Often, people refer to dates as the "second Friday in August, 2018" or the "fourth Sunday in March, 2012". But it's hard to tell what date that is! Your task to is to write a program that receives a year, a month, a day of the week, and an integer, and output that date.

Challenge

• For input, you will get a year, a month, a day of week, and a number.




• You can take input in any reasonable format, like using a string for the day of week or using a zero indexed weekday, or even take the year and month in a single string. Do explain your input format in your answer, though.




• The integer that tells you which day of week in the month to target will be an integer from 1-5. The integer will never refer to a day of week that does not exist(e.g. the fifth Friday of February 2019, which doesn't exist).




• Years will always be positive.




• Your output can be in any reasonable format, including printing your final date. However, please explain your output format un your answer.




• Providing the year and month in the output is optional. Also, you may assume the date is valid.

Example Input and Output

Consider this input, with the format being taking in the year as a 4 digit number, month as an integer, day of week as string, and the ordinal number as an integer:

2019, 3, Saturday, 2

Output:

March 9

This is code-golf, so shortest answer wins.

MATL, 28 27 bytes

'1 'ihYO31:q+t8XOi=!A)i)1XO

This uses three inputs:

• String with month and year: 'March 2019'
  


• String with three letters, first capitalized, indicating day of the week: 'Sat'


• Number: 2.

Output is a string with day, year and month separated with dashes: 09-Mar-2019.

Try it online!

Explanation

Consider inputs 'March 2019', 'Sat', 2.

'1 '    % Push this string

        % STACK: '1 '

ih      % Input string: month and year. Concatenate

        % STACK: '1 March 2019'

YO      % Convert to serial date number

        % STACK: 737485

31:q+   % Create vector [0 1 2 ... 31] and add element-wise

        % STACK: [737485 737486 737487 ... 737515]

t8XO    % Duplicate. Convert to date format 'ddd': day of week in three letters. Gives

        % a 2D char array

        % STACK: [737485 737486 737487 ... 737515], ['Fri'; 'Sat'; 'Sun'; ...; 'Sun']

i=      % Input string: day of week in three letters. Compare element-wise with broadcast

        % STACK: [737485 737486 737487 ... 737515],

        % [0 0 0; 0 0 0; ...; 1 1 1; 0 0 0; ... 1 1 1; ...]

!A      % True for rows containing only 1

        % STACK: [737485 737486 737487 ... 737515], [0 0 ... 1 ... 0 ... 1 ...]

)       % Index: uses the second vector as a mask into the first

        % STACK: [737486 737493 737500 737507 737514]

i)      % Input number. Index

        % STACK: 737493

1XO     % Convert to date format 'dd-mmm-yyyy'. Implicit display

        % STACK: '09-Mar-2019'

SmileBASIC, 58 51 bytes

INPUT M$,D,N

DTREAD M$+"/01"OUT,,,W?D-W+7*N-7*(W<D)

Input is in the form YYYY/MM,weekday,n, (weekday 1 = Sunday).

Output is the day of the month, 1 indexed.

The test case would be 2019/03,7,2 → 9

Explanation:

INPUT YEAR_MONTH$,WEEKDAY,N



'get the day of the week (0 indexed) of the first day in the month

DTREAD YEAR_MONTH$+"/01" OUT y,m,d,WEEKDAY_1



'get the day of the month of the first <WEEKDAY>

'(This might be less than 1, which is fixed later)

FIRST = (WEEKDAY-WEEKDAY_1)



'Add 7*N to get the (N+1)th (or Nth, if FIRST was less than 1) <WEEKDAY> in that month.

FIRST = FIRST + 7*N



'If FIRST was not less than 1 to begin with, subtract 7 to get the proper date

PRINT FIRST - 7*(WEEKDAY_1<WEEKDAY)

JavaScript (ES6), 49 bytes

f=

(y,m,d,n)=>(d+6-new Date(y,m,7).getDay())%7+n*7-6

<div oninput=o.textContent=f(+y.value,+m.value,+d.value,+n.value)>Year: <input id=y type=number value=2019><br>Month: <select id=m><option value=0>Jan<option value=1>Feb<option value=2>Mar<option value=3>Apr<option value=4>May<option value=5>Jun<option value=6>Jul<option value=7>Aug<option value=8>Sep<option value=9>Oct<option value=10>Nov<option value=11>Dec</select><br>Day: <select id=d><option value=0>Sun<option value=1>Mon<option value=2>Tue<option value=3>Wed<option value=4>Thu<option value=5>Fri<option value=6>Sat</select><br>Count: <input id=n type=number value=1 min=1 max=5><pre id=o>

Month and day of week (starting on Sunday) are zero-indexed.

PHP, 46, 43 bytes

function f($s){echo date(d,strtotime($s));}

Try it online!

The function receives as input a string like "second saturday of March 2019"

The function returns the day number.

Japt, 19 17 14 bytes

Input is: year, 0-based index of month, 0-based index of day & n.

_XµW¶Ze}f@ÐUVX

Try it