在我们的c++课程中,他们建议不要再在新项目中使用c++数组。据我所知,Stroustroup本人建议不要使用数组。但是否存在显著的性能差异?


当前回答

下面是简单的测试:

c++数组vs Vector性能测试说明

与“对向量和数组/指针的基本索引、解引用和增量操作生成的汇编代码的比较”的结论相矛盾。

数组和向量之间一定有区别。测试是这么说的…试试吧,代码就在那里……

其他回答

向量使用的内存比数组多一点,因为它们包含数组的大小。它们还会增加程序的硬盘大小,可能还会增加程序的内存占用。这些增加很小,但如果您使用的是嵌入式系统,则可能很重要。尽管这些差异很重要的大多数地方都是使用C而不是c++的地方。

下面是简单的测试:

c++数组vs Vector性能测试说明

与“对向量和数组/指针的基本索引、解引用和增量操作生成的汇编代码的比较”的结论相矛盾。

数组和向量之间一定有区别。测试是这么说的…试试吧,代码就在那里……

There is no argument about which of them is the best or good to use.They both have there own use cases,they both have their pros and cons.The behavior of both containers are different in different places.One of the main difficulty with arrays is that they are fixed in size if once they are defined or initialized then you can not change values and on the other side vectors are flexible, you can change vectors value whenever you want it's not fixed in size like arrays,because array has static memory allocation and vector has dynamic memory or heap memory allocation(we can push and pop elements into/from vector) and the creator of c++ Bjarne Stroustrup said that vectors are flexible to use more than arrays.

应该避免使用带有new的c++数组(即使用动态数组)。有一个问题是,你必须跟踪它们的大小,你需要手动删除它们,并做所有的家务工作。

我们还可以很容易地在向量中插入、推入和拉出值,这在数组中是不容易做到的。

如果我们讨论性能,那么如果你处理小的值,那么你应该使用数组,如果你处理大规模的代码,那么你应该使用向量(向量比数组更擅长处理大的值)。

STL is a heavily optimized library. In fact, it's even suggested to use STL in games where high performance might be needed. Arrays are too error prone to be used in day to day tasks. Today's compilers are also very smart and can really produce excellent code with STL. If you know what you are doing, STL can usually provide the necessary performance. For example by initializing vectors to required size (if you know from start), you can basically achieve the array performance. However, there might be cases where you still need arrays. When interfacing with low level code (i.e. assembly) or old libraries that require arrays, you might not be able to use vectors.

可能会有一些边缘情况,你在内联函数中有一个向量访问在内联函数中,你已经超出了编译器将内联的范围,它将强制函数调用。这种情况太罕见了,不值得担心——总的来说,我同意litb的观点。

我很惊讶居然没有人提到这一点——不要担心性能,直到它被证明是一个问题,然后进行基准测试。