hedgezzz的部落格

    vector<int> v{1,2,3,4,5,6,7,8,9} ;
    int n = 3 ;
    auto fun([n](int i){return i%n ==0;}) ;
    
    auto t1 = std::chrono::high_resolution_clock::now();
    int inum = count_if(v.begin(),v.end(),std::cref(fun)) ;
    auto t2 = std::chrono::high_resolution_clock::now();
    auto difference = std::chrono::duration_cast<std::chrono::microseconds>(t2 - t1);
    std::cout << difference.count() << std::endl ;
    
    cout << inum << endl ;

http://www.drdobbs.com/cpp/efficient-use-of-lambda-expressions-and/232500059