Input a number and return day of week

Question

Not restricted to any one programming language.

What I'm saying is you pass 1 to it and it returns Monday, 7 corresponds with sunday and so on.

I've managed a 146 byte statement in Java to do the same.

return (n<1?"invalid":(n<2?"monday":(n<3?"tuesday":(n<4?"wednesday":(n<5?"thursday":(n<6?"friday":(n<7?"saturday":(n<8?"sunday":"invalid"))))))));

Your program should:

• output full words (STDOUT)
• not crash if the input is less than 1 or greater than 7

Answer 1

R, 61

a=format(Sys.Date()+0:15,"%A");a[grep("^M",a)[1]+0:6][scan()]

format(Sys.Date()+0:15,"%A") outputs the day of the week of today and the 15 following days. grep("^M",a)[1]+0:6 is the index of the first monday in that sequence and the six following days.

Usage:

> a=format(Sys.Date()+0:15,"%A");a[grep("^M",a)[1]+0:6][scan()]
1: 7
2: 
Read 1 item
[1] "Sunday"
> a=format(Sys.Date()+0:15,"%A");a[grep("^M",a)[1]+0:6][scan()]
1: 4
2: 
Read 1 item
[1] "Thursday"
> a=format(Sys.Date()+0:15,"%A");a[grep("^M",a)[1]+0:6][scan()]
1: 2
2: 
Read 1 item
[1] "Tuesday"
> a=format(Sys.Date()+0:15,"%A");a[grep("^M",a)[1]+0:6][scan()]
1: 8
2: 
Read 1 item
[1] NA

Answer 2

Golfscript (50 55)

Expects the input number to be on the stack.

" Mon Tues Wednes Thurs Fri Satur Sun"" "/\="day"+

or

("Mon Tues Wednes Thurs Fri Satur Sun"" "/\="day"+

or (for 51, but it's just fun)

"day Mon Tues Wednes Thurs Fri Satur Sun"" "/.@=\0=

The requirement "not crash" is pretty lenient. This will just print "day" for invalid input – which is not a crash, so it should be allowed.

Answer 3

CJam - 47 or 45

qi"Sun Mon Tues Wednes Thurs Fri Satur"S/="day"

Try it at http://cjam.aditsu.net/

If I can assume that the number is already on the stack, then the first 2 characters can be removed.

Answer 4

C# - 28

According to your reference solution, this should be valid.

It assumes the input is stored in the variable i and outputs "Sunday", "Monday", etc for 0, 1, etc respectively.

If i is out of bounds (below 0 or above 7), i will be output. (This is valid because the program doesn't crash)

Console.Write((DayOfWeek)i);

If you actually want a working function, here is one using 48 bytes:

string f(int i){return((DayOfWeek)i)+"";}

Answer 5

Python - 83 76

from datetime import*
i=input()
if 0<i<8:print date(2013,7,i).strftime("%A")

July 2013 was the first month I found that had monday as its first day. Rest of this is quite self explanatory.

Answer 6

Java 8, 48 chars

return n>0&n<8?DayOfWeek.of(n).name():"Invalid";

With java 8 comes new enum DayOfWeek, that provides non locale dependent data.

For java 7 and older, this should work good too (76 chars):

return n<1|n>7?"Invalid":DateFormatSymbols.getInstance().getWeekdays()[n+1];

And locale fixed variant (90 chars):

return <1|n>7?"Invalid":DateFormatSymbols.getInstance(Locale.ENGLISH).getWeekdays()[n+1];

Answer 7

C, 81

Just for fun...

printf("%sday\n","Mon\0Tues\0Wednes\0Thurs\0Fri\0Satur\0Sun"+"  $)06:@"[n&7]-32);

Answer 8

Java

Uses local language:

return i<1||i>7?"Error":new DateFormatSymbols().getWeekdays()[i];

Answer 9

C, 117

Also just for fun...

d(n){for(char*p="\177MvT|WpF S\177oxh`a`t\026uze|d;n|eHrrspi\001d\001a\001y\001\n";
*p;p++)-*p++&1<<n-1&&putchar(*p);}

(I realize this isn't an obfuscation challenge. I just wanted to see how far a purely data-driven bit-test loop could be golfed.)

---

The un-golfed version:

void d(int n)
{
  char *p =
    "\177" "M"   "\166" "T"   "\174" "W"   "\160" "F"   "\040" "S"
    "\177" "o"   "\170" "h"   "\140" "a"   "\140" "t"   "\026" "u"
    "\172" "e"   "\174" "d"   "\073" "n"   "\174" "e"   "\110" "r"
    "\162" "s"   "\160" "i"   "\001" "d"   "\001" "a"   "\001" "y"
    "\001" "\n";

  for (; *p; p++)
    if (-(*(p++)) & (1<<(n-1)))
      putchar(*p);
}

Driver:

int main() { for (int n = 1; n <= 7; n++) d(n); }

Output:

Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Sunday

---

How it works:

• The character string consists of a pairs of bit-flags and output characters.
• The even indexes are the bit-flags ('\177', 'v', '|', 'p', ' ', etc.) — but they are stored in ones-complement form to minimize the number of nonprintable ASCII values, which are expensive because they have to be encoded in octal.
• The odd indexes are the output characters ('M', 'T', 'W', 'F', 'S', 'o', 'h', 'a', etc.).

Answer 10

Batch - 114 Bytes

@cmd/von/c"for %%a in (1Mon 2Tues 3Wednes 4Thur 5Fri 6Satur 7Sun)do @set a=%%a&if "!a:~0,1!"=="%1" echo !a:~1!day"

The first part @cmd/von/c is starting up a new cmd session - it uses the /v switch to enable delayed variable expansion, which saves adding in the lengthy setLocal enableDelayedExpansion. This way you only need to add the @ symbol (to hide output) before the cmd command and in the middle of the for loop, instead of @echo off at the start of the script.

Answer 11

PHP - 32

Day is given as $i

<?echo date('l',(($i+4)*86400));

Answer 12

bash - 18

date +%A -d01010$1

Save it in a file, e.g. day.sh, then run

./day.sh 1 # output: Monday
./day.sh 2 # output: Tuesday
...

Answer 13

R, 37

The obligatory hack solution with R.

weekdays(as.Date((paste0("1/1/",n))))

where the input is first stored as variable n. Turning this into a named function would be longer:

d=function(n) weekdays(as.Date((paste0("1/1/",n))))

Answer 14

Javascript - 63

'0Mon0Tues0Wednes0Thurs0Fri0Satur0Sun'.split(0)[prompt()]+'day'

Answer 15

C# - 30

Since the provided example doesn't actually output, neither does this. Also I'm assuming we don't have to have an error message if the value is below 1 or over 7.

((DayOfWeek)(n%7)).ToString();

For an error message (47):

n<1|n>7?"Error":((DayOfWeek)(n%7)).ToString();

The reason for the %7 is because DayOfWeek begins with Sunday.

Small cheat: DayOfWeek is contained in the System namespace, so if using System; isn't specified elsewhere (usually always is), you'd need to replace DayOfWeek with System.DayOfWeek -- an additional 7 characters.