C 中的 MAX 和 MIN 是什么？#定义函数
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What are the MAX and MIN in C? #define function
提问by José Algarra
I am a student and my teacher gave me and exercise already solved for studying, in his exercise I see this line:
我是一名学生，我的老师给了我并且已经解决了学习的练习，在他的练习中我看到了这一行：
#define MIN(a,b) ((a) < (b) ? (a) : (b))
I never used the #define before.
我以前从未使用过#define。
I do not understand what:
我不明白什么：
((a) < (b) ? (a) : (b))
stands for.
代表。
Looks like if '?' was a comparer not sure. Anybody can help me?
看起来像如果 '?' 是一个比较者不确定。任何人都可以帮助我吗？
回答by RvdK
It's called the conditional operator (or ternary operator)
它被称为条件运算符（或三元运算符）
#define MIN(a,b) ((a) < (b) ? (a) : (b))
Means:
方法：
if ((a) < (b)){
return a;
} else {
return b;
}
So if you would do:
所以如果你会这样做：
int test = MIN(5,10);
test would be 5
测试将是 5
Troubles linking to the wiki page: http://goo.gl/bw2sL
无法链接到 wiki 页面：http: //goo.gl/bw2sL
回答by 111111
#definedefines a new preprocessor macro, which in this case place's the MIN code at the point where you place it; with the aand b"variables" being replaced with whatever you gave to the macro as inputs.
#define定义了一个新的预处理器宏，在这种情况下，它将 MIN 代码放置在您放置它的位置；随着a与b“变量”正在与任何替换你给宏作为输入。
#define MIN(a,b) ((a) < (b) ? (a) : (b))
MIN(5,6);
//gets expanded to
((5) < (6) ? (5) : (6))
The actual expression is using the ternary operator to, do return either A or B depending on the evaluation of the expression, you can read more about it here:
实际表达式使用三元运算符，根据表达式的计算返回 A 或 B，您可以在此处阅读有关它的更多信息：
http://en.cppreference.com/w/cpp/language/operator_other
http://en.cppreference.com/w/cpp/language/operator_other
Finally, as you marked your question with c++, please consider the non macro max and min functions.
最后，当您用 C++ 标记您的问题时，请考虑非宏 max 和 min 函数。
#include <algorithm>
...
int i=std::min(5,6);
