C ++ Long switch语句或查找地图？ [英] C++ Long switch statement or look up with a map?

问题描述

在我的C ++应用程序中，我有一些值作为代码来表示其他值。为了翻译代码，我一直在辩论使用switch语句或stl地图。切换将如下所示：

In my C++ application, I have some values that act as codes to represent other values. To translate the codes, I've been debating between using a switch statement or an stl map. The switch would look something like this:

int code;
int value;
switch(code)
{
case 1:
    value = 10;
    break;
case 2:
    value = 15;
    break;
}

映射将是 stl :: map< int，int> 并且翻译将是一个简单的查找代码用作键值。

The map would be an stl::map<int, int> and translation would be a simple lookup with the code used as the key value.

哪一个更好/更高效/清洁/接受？为什么？

Which one is better/more efficient/cleaner/accepted? Why?

推荐答案

就我个人而言，我会使用地图，因为它的用途意味着数据查找 - 在程序行为。此外，使用映射比使用开关更容易修改数据映射。

Personally, I would use the map, as its use implies a data lookup - using a switch usually indicates a difference in program behavior. Furthermore modifying the data mapping is easier with a map than with a switch.

如果性能是一个真正的问题，分析是获得可用答案的唯一方法。如果分支错误预测经常发生，开关可能不会更快。

If performance is a real issue, profiling is the only way to get a usable answer. A switch may not be faster if branch mispredictions happen often enough.

另一种想法是，如果将代码和相关联的值转换为数据结构，特别是如果代码和值的范围是静态的：

Another approach to think about this is if it wouldn't make more sense to combine the code and the associated value into a datastructure, especially if the range of codes and values is static:

struct Code { int code; int value; };

Code c = ...

std::cout << "Code " << c.code << ", value " << c.value << std::end;

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