加载中…
注意逻辑运算符的优先级
(2006-10-15 00:11:08)| 分类： About OI |
刚才做一道题，跟答案总不一样，百思不得其解……
若A=11001010B,B=00001111B,C=01011100B,则A∨B∧C=(
)B
A)01011110 B)00001111
C)01011100 D)11001110
E)11001010
A)01011110
我算下总是01001100，可答案是D.11001110
后来不知道怎么一下就想通了，原来是优先级的问题。
规定优先级的顺序为
，若有括号时，先进行括号内运算。
，若有括号时，先进行括号内运算。这样应该先算 ∧ 后算 ∨ 答案就对了。
附录
真值表：
重要等值式：
１、交换律Ａ∨Ｂhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＢ∧Ａ
２、结合律（Ａ∨Ｂ)∨Ｃhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ∧(Ｂ∧Ｃ)
３、分配律Ａ∨（Ｂ∧Ｃ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gif（Ａ∨Ｂ）∧（Ａ∨Ｃ）
Ａ∧（Ｂ∨Ｃ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gif（Ａ∧Ｂ）∨（Ａ∧Ｃ）
４、德－摩根律（Ａ∨Ｂ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ∧Ｂ，（Ａ∧Ｂ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ∨Ｂ
５、等幂律Ａ∨Ａhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ，Ａ∧Ａhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ
６、吸收律Ａ∨（Ａ∧Ｂ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ，Ａ∧（Ａ∨Ｂ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ
７、零律Ａ∨１http://www.chinaschool.org/kcgg/jiaofa/images/s14.gif１，Ａ∧０http://www.chinaschool.org/kcgg/jiaofa/images/s14.gif０
８、同一律Ａ∨０http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ，Ａ∧１http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ
９、互否律Ａ∨Ａhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gif１(排中律)，Ａ∧Ａhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gif０(矛盾律)
10、双重否定律（Ａ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ
11、蕴涵等值式ＡＢhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ∨Ｂ
12、等价等值式ＡＢhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gif（ＡＢ）∧（ＢＡ）
13、假言易位ＡＢhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＢＡ
14、等价否定等值式ＡＢhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡＢ
15、归谬论（ＡＢ）∧（ＡＢ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ
２、结合律（Ａ∨Ｂ)∨Ｃhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ∧(Ｂ∧Ｃ)
３、分配律Ａ∨（Ｂ∧Ｃ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gif（Ａ∨Ｂ）∧（Ａ∨Ｃ）
Ａ∧（Ｂ∨Ｃ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gif（Ａ∧Ｂ）∨（Ａ∧Ｃ）
４、德－摩根律
（Ａ∨Ｂ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ∧Ｂ，（Ａ∧Ｂ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ∨Ｂ５、等幂律Ａ∨Ａhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ，Ａ∧Ａhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ
６、吸收律Ａ∨（Ａ∧Ｂ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ，Ａ∧（Ａ∨Ｂ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ
７、零律Ａ∨１http://www.chinaschool.org/kcgg/jiaofa/images/s14.gif１，Ａ∧０http://www.chinaschool.org/kcgg/jiaofa/images/s14.gif０
８、同一律Ａ∨０http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ，Ａ∧１http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ
９、互否律Ａ∨
Ａhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gif１(排中律)，Ａ∧Ａhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gif０(矛盾律)10、双重否定律
（Ａ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ11、蕴涵等值式Ａ
Ｂhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ∨Ｂ12、等价等值式Ａ
Ｂhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gif（ＡＢ）∧（ＢＡ）13、假言易位Ａ
Ｂhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＢＡ14、等价否定等值式Ａ
Ｂhttp://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡＢ15、归谬论（Ａ
Ｂ）∧（ＡＢ）http://www.chinaschool.org/kcgg/jiaofa/images/s14.gifＡ
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