相关疑难解决方法(0)

我刚刚阅读了这篇博客http://lemire.me/blog/archives/2012/06/20/do-not-waste-time-with-stl-vectors/,比较了operator[]作业的性能和push_back预留的内存std::vector,我决定亲自尝试一下 操作很简单:

// for vector
bigarray.reserve(N);

// START TIME TRACK
for(int k = 0; k < N; ++k)
   // for operator[]:
   // bigarray[k] = k;
   // for push_back
   bigarray.push_back(k);
// END TIME TRACK

// do some dummy operations to prevent compiler optimize
long sum = accumulate(begin(bigarray), end(array),0 0);

这是结果:

 ~/t/benchmark> icc 1.cpp -O3 -std=c++11
 ~/t/benchmark> ./a.out
[               1.cpp:   52]     0.789123s  --> C++ new
[               1.cpp:   52]     0.774049s  --> C++ new
[               1.cpp: …