是std :: copy比std :: cout更快的输出? [英] is std::copy faster than std::cout for output?

问题描述

  std :: vector< int>v {2,4,6,8,10,12,14,16,18,20};//打印数字std :: copy(v.cbegin()，v.cend()，std :: ostream_iterator< int>(std :: cout，")));std :: cout<<'\ n'; 

此处std :: copy用于写入标准输出.这比在for循环中对向量元素使用std :: cout更快

  for(自动元素:v)std :: cout<<元素<<"; 

我找不到有关它们如何写入两者的输出缓冲区的太多信息.

解决方案

要大致了解两者的相对性能，请在此处查看基准测试结果:

here std::copy is used to write to std out. Is this faster than using std::cout for the vector elements in a for loop like

for(auto element: v) std::cout << element << " ";

I could't find much information about how they would write to output buffers for both.

解决方案

To give an rough idea on the relative performance of the two, see the benchmark results here: http://quick-bench.com/wGYYPBXEgvLrkyp5gpJOnIpt7A4

I had to output to a std::stringstream instead of std::cout to keep quick-bench happy. It gives some insight on the raw performance of the underlying implementations, but not on how they crossplay with a highly OS dependent output stream like std::cout.

So it is hard to come to any definitive conclusions based on such a simple benchmark alone. I would take from this that in reality there is most likely not enough difference between the two approaches to prefer one over the other from a performance perspective.

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