Given a string of printable ASCII characters, convert them all to lowercase, except not just the letters.

ASCII characters that are letters have a bit in their binary representation that is 0 for uppercase, and 1 for lowercase. Setting this bit to 1 for a non-letter character that previously had it set to 0 results in it changing to a completely unrelated character, which for this challenge we will call the lowercase version of that character.

Input

• A sequence of characters, each of which is a printable ASCII character (character codes 32 to 126 inclusive)
• This may be a string or any ordered data structure of characters
• There will never be an underscore _ (character code 95) as its lowercase version is character code 127, which is outside the printable range and used as a control character

Output

• A sequence of the same number of characters as the input
• This may be a string or any ordered data structure of characters. It does not need to match the input format (provided it is consistent between inputs)
  • For example, you may take input as an array of characters, and output as a string, provided this format does not change for different inputs
• Each character is either the same as the input, if it was a lowercase version already, or otherwise the lowercase version of the input character

Examples

A letter

Character "A" is character code 65, or 1000001 in binary. The bit in position 5 from the right, representing $2^5$, is 0. Setting this bit to 1 gives 1100001, or 97, which is the character code for "a". So the lowercase version of "A" is "a", as expected.

A non-letter

Character "^" is character code 94, or 1011110 in binary. The bit in position 5 from the right, representing $2^5$, is 0. Setting this bit to 1 gives 1111110, or 126, which is the character code for "~". So the lowercase version of "^" is "~".

Test cases

Test cases are in the format "input" : "output"

Note that " and \ have both been escaped with a preceding \, because they are enclosed in double quotes, but each still represents a single character)

" " : " "
"!" : "!"
"\"" : "\""
"#" : "#"
"$" : "$"
"%" : "%"
"&" : "&"
"'" : "'"
"(" : "("
")" : ")"
"*" : "*"
"+" : "+"
"," : ","
"-" : "-"
"." : "."
"/" : "/"
"0" : "0"
"1" : "1"
"2" : "2"
"3" : "3"
"4" : "4"
"5" : "5"
"6" : "6"
"7" : "7"
"8" : "8"
"9" : "9"
":" : ":"
";" : ";"
"<" : "<"
"=" : "="
">" : ">"
"?" : "?"
"@" : "`"
"A" : "a"
"B" : "b"
"C" : "c"
"D" : "d"
"E" : "e"
"F" : "f"
"G" : "g"
"H" : "h"
"I" : "i"
"J" : "j"
"K" : "k"
"L" : "l"
"M" : "m"
"N" : "n"
"O" : "o"
"P" : "p"
"Q" : "q"
"R" : "r"
"S" : "s"
"T" : "t"
"U" : "u"
"V" : "v"
"W" : "w"
"X" : "x"
"Y" : "y"
"Z" : "z"
"[" : "{"
"\\" : "|"
"]" : "}"
"^" : "~"
"`" : "`"
"a" : "a"
"b" : "b"
"c" : "c"
"d" : "d"
"e" : "e"
"f" : "f"
"g" : "g"
"h" : "h"
"i" : "i"
"j" : "j"
"k" : "k"
"l" : "l"
"m" : "m"
"n" : "n"
"o" : "o"
"p" : "p"
"q" : "q"
"r" : "r"
"s" : "s"
"t" : "t"
"u" : "u"
"v" : "v"
"w" : "w"
"x" : "x"
"y" : "y"
"z" : "z"
"{" : "{"
"|" : "|"
"}" : "}"
"~" : "~"
"([({Enclosed})])" : "({({enclosed})})"
"A@B.c" : "a`b.c"

Rules

• There is no requirement to use bitwise operations to achieve the correct output
• Provided your output is correct for each input, your code is valid

Explanations are optional, but I'm more likely to upvote answers that have one.

posted 8 months ago

CC BY-SA 4.0

trichoplax‭

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