Sorting CharacterVector

a <- c(letters, LETTERS)

Sys.setlocale(locale = "C")

## [1] "C/C/C/C/C/zh_TW.UTF-8"

sort(a)

##  [1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q"
## [18] "R" "S" "T" "U" "V" "W" "X" "Y" "Z" "a" "b" "c" "d" "e" "f" "g" "h"
## [35] "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s" "t" "u" "v" "w" "x" "y"
## [52] "z"

Sys.setlocale(locale = "en_US.UTF-8")

## [1] "en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/zh_TW.UTF-8"

sort(a)

##  [1] "a" "A" "b" "B" "c" "C" "d" "D" "e" "E" "f" "F" "g" "G" "h" "H" "i"
## [18] "I" "j" "J" "k" "K" "l" "L" "m" "M" "n" "N" "o" "O" "p" "P" "q" "Q"
## [35] "r" "R" "s" "S" "t" "T" "u" "U" "v" "V" "w" "W" "x" "X" "y" "Y" "z"
## [52] "Z"