(string= "abc" "abc") ;=> t
(string= "abc" "ABC") ;=> nil
(string= "AB" "ABC") ;=> nil
(length "abcdefg") ;=> 7
(length "日本語") ;=> 3
; 普通に結合
(concat "abc" "-def") ;=> "abc-def"
(concat "私は" "美味しく食べました") ;=> "私は美味しく食べました"
; nilは無視
(concat "abc" nil "-def")
; 引数なしの場合は空文字列を返す
(concat) ;=> ""
(upcase "The cat in the hat") ;=> "THE CAT IN THE HAT"
(downcase "THE CAT IN THE HAT") ;=> "the cat in the hat"
(capitalize "The cat in the hat") ;=> "The Cat In The Hat"
(capitalize "THE 77TH-HATTED CAT") ;=> "The 77th-Hatted Cat"
; 0(a)から、3(d)なので"abc"を生成
(substring "abcdefg" 0 3) ;=> "abc"
; 負の添え字は逆から数える
(substring "abcdefg" -3 -1) ;=> "ef"
; 第2引数は省略可能で、終端までコピーを表す
(substring "abcdefg" 2) ;=> "cdefg"
; 先頭に0を渡すと文字列のコピーと等価になる
(substring "abcdefg" 0) ;=> "abcdefg"
(split-string "Soup is good food" "o") ;=> ("S" "up is g" "" "d f" "" "d")
(split-string "Soup is good food" "o+") ;=> ("S" "up is g" "d f" "d")