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http://answers.yahoo.com/question/index?qid=20070927145356AAjwuaU

! means logical not.
&& means logical and.
1 && 1 得1
1 && 0 得0
0 && 1 得0
0 && 0 得0

|| means logical or.

if (statement1 && statement2)  // 如果statement1不成立, 就不會check statement2
                                                  // 如果statement1成立, 就會 check statement2
                                                 //  如果statement1成立->check statement2, 但是statement2不成立-->



The following code is correct.
It will evaluate x.
If you need further explanation of these, look at truth tables.
 If x equals 0, then it will evaluate y. If y also equals 0 then it will output blah blah, otherwise it will not.


If (x == 0 && y == 0)
{
cout << "blah blah";
}

If (x == 0 || y == 0)
{
cout << "blah blah";
}

To use the ! symbol, this will only output blah blah if the expression evaluates to false, that is both x and y equal 0.
If (!(x == 0 || y == 0))
{
cout << "blah blah";
}

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※ 作者: rikaka 時間: 2012-03-27 14:39:45
※ 編輯: rikaka 時間: 2012-03-27 15:39:46