//count是一个计算某元素给定范围出现次数的操作
vector<int> vec{ 1, 2, 3, 3, 2, 2, 25, 6, 7, 8, 2 };
vector<double> vdc{12, 34, 56, 78};
cout << count(vdc.cbegin(), vdc.cend(), 12)<<endl;//不同类型,但是操作一样
cout<<count(vec.cbegin(), vec.cend(), 2)<<endl;
return 0;
vector<string> L = { "aa", "aaa", "aa", "cc" };
string sum = accumulate(L.cbegin(), L.cend(), string());//传递""是不可以的
vector<double> L = {1.1 ,2,3,4,5 };
double sum = accumulate(L.cbegin(), L.cend(), 0.0);//0会损失精度
std::equal(roster1.cbegin(), roster1.cend(), roster2.cbegin());
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vector<int> a{ 1, 2, 3, 4, 5, 6, 7, 8, 9 };
fill_n(a.begin(), a.size(), 0);