do-while 循環由 do 關鍵字開始，后跟循環體表達式。其后跟while 關鍵字，然后是一個 開口的圓括號 (，再跟條件表達式和一個閉口的圓括號 ) ： > A do-while loop starts with the do keyword followed by the loop body expression. After that follows the while keyword, an opening parenthesis (, the condition expression and a closing parenthesis ): ~~~ do expression while(condition); ~~~ 條件表達式必須為Bool類型。 > The condition expression has to be of type Bool. 如語法所暗示的，循環體表達式至少會執行一次，這和 while循環（第5.14節）不同。 > As the syntax suggests, the loop body expression is always evaluated at least once, unlike while (5.14) loops.