if and only if

短语

当且仅当

发音

UK /ɪf ən(d)ˈəʊn.li ɪf/
其它
US /ɪf ən(d)ˈoʊn.li ɪf/

别名

iff

释义与例句

conj.
  1. 1.

    Is equivalent to; implies and is implied by; is true and false in the same cases as.

    当且仅当

    若且唯若

    数学 哲学

    A rectangle is a square if and only if all four of its sides have the same length.

    An integer is even if and only if its square is also even.

  2. 2.

    Synonym of if (with added intensity)

    非正式 引申义

    I'll let you go to the concert if and only if you clean your room.