コピーと置換を同時に行ないたい
s1 = 'this is huge?' s2 = s1.sub(/this/, 'that') p s1 #=> "this is huge?" p s2 #=> "that is huge?" s3 = 'this is huge?' p s3.sub!(/this/, 'that') #=> "that is huge?" p s3.sub!(/this/, 'that') #=> nil
直接,対象の文字列を置換したい場合は,sub!を使う.
置換が発生しない場合,sub!の返り値はnilになる.