いつも忘れてしまう。
string f(char c) { switch (c) { case 'a': .. case 'z': return "Lower letter!"; case 'A': .. case 'Z': return "Upper letter!"; default: return "Non-alphabetical character!"; } assert(false); } unittest { assert(f('f') == "Lower letter!"); assert(f('F') == "Upper letter!"); assert(f(' ') == "Non-alphabetical character!"); }