Duplicate & switch case

Question

The goal is, having taken a string as input, duplicate each latin letter and "toggle" its case (i.e. uppercase becomes lowercase and vice-versa).

Example inputs & outputs:

Input      Output
bad        bBaAdD
Nice       NniIcCeE
T e S t    Tt eE Ss tT
s E t      sS Ee tT
1!1!1st!   1!1!1sStT!
n00b       nN00bB     
(e.g.)     (eE.gG.)
H3l|@!     Hh3lL|@!

The input consists of printable ASCII symbols.

You shouldn't duplicate non-latin letters, numbers, special chars.

Answer 1

Python, 56 54 bytes

lambda s:''.join(c+c.swapcase()*c.isalpha()for c in s)

Test it on Ideone.

Answer 2

JavaScript ES6, 70 68 66 64 bytes

Saved 2 bytes thanks to @Kevin Lau - not Kenny

Saved 2 bytes thanks to @Cᴏɴᴏʀ O'Bʀɪᴇɴ

s=>s.replace(/[A-Z]/gi,l=>l+l[`to${l<"a"?"Low":"Upp"}erCase`]())

Explanation

This uses a really hacky:

l[`to${l<"a"?"Low":"Upp"}erCase`]()

which ungolfed is:

l[`to${
   l < "a" ?
   "Low" : 
   "Upp"
}erCase`]()

Basically l < "a" checks if the code point of the letter is less then the code point of a (therefore being an uppercase letter). If it is it'll do to + Low + erCase which becomed l['toLowerCase']() and makes the character lowercase. ` quotes allow string formatting so essentially you can think of:

`to${l < "a" ?"Low" : "Upp"}erCase`

as: "to" + (l<"a" ? "Low" : "Upp") + "erCase" which generates the function to call (make the string upper or lower case). We put this in square brackets [ ... ] which lets us access a property given its name as a string. This returns the appropriate function and then we just call it.

Answer 3

Jelly, 5 bytes

żŒsQ€

Try it online!

How it works

żŒsQ€  Main link. Argument: s (string)

 Œs    Yield s with swapped case.
ż      Zip s with the result.
   Q€  Unique each; deduplicate each pair of characters.

Answer 4

Ruby, 37 33 (30 + -p flag) bytes

swapcase to the rescue! Sort of. -4 bytes from @Lynn.

gsub(/[a-z]/i){$&+$&.swapcase}

Answer 5

C, 63 60 bytes

f(char*s){for(;*s;s++)isalpha(putchar(*s))&&putchar(32^*s);}

Uses the fact that 'a' XOR 32 == 'A', etc.

Three bytes saved thanks to FryAmTheEggman.

Answer 6

CJam, 11 bytes

l_el_eu.+.|

Test it here.

Explanation

l      e# Read input.
_el    e# Duplicate, convert to lower case.
_eu    e# Duplicate, convert to upper case.
.+     e# Concatenate the two characters in matching positions from those two
       e# strings. E.g. "ab!" "AB!" would give ["aA" "bB" "!!"].
       e# For each character from the original string and the corresponding 
.|     e# string from this list, take the set union (which eliminates duplicates
       e# and keeps the order the values appear in from left to right, so that
       e# the original case of each letter comes first).

Answer 7

Pyth, 7 bytes

sm{+dr2

Test suite.

sm{+dr2    input: Q
sm{+dr2dQ  implicit arguments

        Q  input
 m         for each character as d:
     r2d       swapcase
   +d          prepend d
  {            deduplicate
s          join as string

Answer 8

Python 3.5, 60 56 bytes:

for i in input():print(end=i+i.swapcase()[:i.isalpha()])

A full program. Will try to golf more.

Try It Online! (Ideone)

Answer 9

Haskell, 73 bytes

l=['a'..'z']
u=['A'..]
(>>= \c->c:maybe""pure(lookup c$zip l u++zip u l))

Answer 10

Cheddar, 118 104 bytes

(s)->s.chars.map((i)->{if String.letters has i.lower{if i<"a"{i+i.lower}else{i+i.upper}}else{i}}).join()

First real Cheddar answer!!! This is a lot less climactic than I thought it would be... ;_;

Works with release 1.0.0-beta.9, non-competing.

---

As you can tell I didn't design cheddar to be golfy :/

Ungolfed:

(str) -> str.chars.map(
    (i) -> {
        if String.letters has i {
            if i < "a" { // Check char code, meaning it's upper case if true
                i+i.lower
            }
            else {
                i+i.upper
            }
        } else {
            i
        }
    }
).join()

Usage:

var doThing = <code here>;
doThing("input...");

---

Update: 7/14/16 I've finished ternaries making this come down to 84 bytes

Cheddar, 84 bytes

(s)->s.chars.map((i)->String.letters has i.lower?i<"a"?i+i.lower:i+i.upper:i).join()

works as of version v1.0.0-beta.14

Answer 11

Retina, 28 27 21 bytes

Those are tabs, not spaces.

.
$&  $&
T`lL    p`Ll_`  .

Try it online

Thanks for the suggestions everyone.

Answer 12

C, 87 80

Pass a string as input to f() and the output is written to STDOUT. The string is not modified.

f(char*v){for(;*v;++v)putchar(*v),isalpha(*v)?putchar(*v-32+64*!islower(*v)):0;}

Answer 13

sed, 30 bytes

29 bytes code + 1 byte parameter -r

s/([a-z])|([A-Z])/&\u\1\l\2/g

Usage:

echo -e 'bad\nNice\nT e S t\ns E t\n1!1!1st!\nn00b\n(e.g.)\nH3l|@!' |\
sed -r 's/([a-z])|([A-Z])/&\u\1\l\2/g'

Answer 14

J, 31 29 bytes

[:;]<@~."1@,.tolower,.toupper

Explanation

[:;]<@~."1@,.tolower,.toupper  Input: s
                      toupper  Convert s to all uppercase
             tolower           Convert s to all lowercase
                    ,.         Join them as columns in a 2d array
   ]                           Identity function, get s
           ,.                  Prepend s as a column to the 2d array
      ~."1@                    Take the unique chars on each row
    <@                         Box them
[:;                            Unbox the list of boxes and join their contents and return

Answer 15

Haskell, 121, 101, 85, 82

import Data.Char
g n|isLower n=toUpper n|1<2=toLower n
(>>= \x->x:[g x|isAlpha x])

Answer 16

Perl, 36 bytes (35 + -n flag)

s/[a-z]/$&.(ord$&<97?lc$&:uc$&)/ige

(-p tag needed)

(-2 bytes thanks to @Dom Hasting)

Short explanation:
ord returns the numeric value of a char. ord(any lower case) >= 97, and ord(any upper case) <= 90).

Run with :

perl -pe 's/[a-z]/$&.(ord$&<97?lc$&:uc$&)/ige'

Answer 17

Ruby, 31+1=32 30+1=31 bytes

With the -p flag, run

gsub(/(?<=(.))/){$1.swapcase!}

Takes advantage of the fact that swapcase! will return nil on anything but an ASCII letter, which translates to an empty string when returned out of the gsub block. @Jordan saved a byte by capturing the previous character in a look-behind.

Answer 18

R, 191 187 168 156 98 99 bytes

99 bytes due to improvements fro Giuseppe and MickyT.

paste0(x<-unlist(strsplit(readline(),"")),gsub("[^A-Za-z]","",chartr("a-zA-Z","A-Za-z",x)),collapse="")

Answer 19

05AB1E, 7 bytes

Code:

vyyš«Ù?

Explanation:

v       # For each in input.
 yyš    # Push y and y swapcased.
    «Ù  # Concatentate and uniquify.
      ? # Print without a newline.

Uses the CP-1252 encoding. Try it online!

Answer 20

Pyke, 8 6 bytes

FDl4+}

Try it here!

Answer 21

V, 21 bytes

Try it online!

Too many bytes...

Ó./°ò
Íá/°°
Îlg~lÎHògJ

Answer 22

Actually, 8 bytes

`;Öo╔`MΣ

Try it online!

Explanation:

`;Öo╔`MΣ
`;Öo╔`M   for each character in input:
 ;          duplicate the character
  Ö         swap case
   o        append to original character
    ╔       remove duplicated characters
       Σ  concatenate

Answer 23

MATL, 11 9 bytes

tYov"@uv!

Try it Online

Explanation

        % Implicitly grab input as string
t       % Duplicate the input
Yo      % Swap case of all characters
v       % Vertically concatenate the original and swap-cased versions
"       % For each column (letter in the original)
  @u    % Compute the unique values (without sorting)
  v!    % Vertically concatenate with the existing output and transpose
        % Implicit end of for loop and implicit display

Answer 24

Common Lisp (Lispworks), 262 bytes

(defun f(s)(let((b""))(dotimes(i(length s))(if(lower-case-p(elt s i))(progn #1=(setf b(concatenate 'string b(string #2=(elt s i))))(setf b(concatenate 'string b(string(char-upcase #2#)))))(progn #1#(setf b(concatenate 'string b(string(char-downcase #2#)))))))b))

ungolfed:

(defun f (s)
  (let ((b ""))
    (dotimes (i (length s))
      (if (lower-case-p (elt s i))
          (progn
           #1=(setf b (concatenate 'string b (string #2=(elt s i))))
           (setf b (concatenate 'string b (string (char-upcase #2#)))))
        (progn
          #1#
          (setf b (concatenate 'string b (string (char-downcase #2#)))))))
    b))

Usage:

CL-USER 1 > (f "abc")
"aAbBcC"

CL-USER 2 > (f "bad")
"bBaAdD"

Answer 25

Perl, 28 22 21 bytes (20 + -p flag)

s/[a-z]/$&.$&^$"/ige

Answer 26

Stax, 7 6 bytes

Thanks to @recursive for a byte saved!

┤§ÆP♦■

Run and debug it at staxlang.xyz! (link is to unpacked version)

Unpacked (7 bytes):

c:~\{um

Explanation:

c:~\{um
c          Copy the top element of the stack (the input, in this case).
 :~        Switch case of each letter in the copy.
   \       Zip. This produces an array of two-character strings.
    { m    Map a block over this array of two-character strings.
     u       Get all unique elements.
           Implicit concatenate and print.

Answer 27

Python, 59 bytes

lambda s:''.join((x,x+x.swapcase())[x.isalpha()]for x in s)

Edited to fix repeating non-alphabetic characters

Answer 28

Julia, 40 bytes

!s=[print(c,isalpha(c)?c$' ':"")for c=s]

Try it online!

Answer 29

PHP 4.1, 57 bytes

This code assumes access through a web server (Apache, for example), using the default configuration.

You can pass the string by sending the key S by any means (POST, GET, COOKIE, SESSION...).

<?for($i=0;$c=$S[$i++];)echo$c,ctype_alpha($c)?$c^' ':'';

Answer 30

C#, 82 71 bytes

s=>string.Concat(s.Select(c=>c+(char.IsLetter(c)?(char)(c^32)+"":"")));

C# lambda where the input and the output are string. Try it online.

11 bytes thanks to @Lynn trick.