泛型编程 - 用模板参数指定策略

模板参数指定策略
示例:标准库函数 sort()
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使用第二个模板参数 ( 比较器 ) 来指定比较的规则(如:降序或升序排列)

#include <iostream>#include <algorithm>using namespace std;void print(int* ar, size_t len) {for (size_t i = 0; i < len; ++i)cout << ar[i] << ' ';cout << '\n';}bool absGreater(int x, int y) {return abs(x) > abs(y);   abs是求绝对值}int main() {int ar[] = { 123, -23, 4, -56, 78, 12 };const size_t N = sizeof(ar) / sizeof(*ar);sort(ar, ar + N, less<int>());    升序排列sort(ar, ar + N, greater<int>()); //降序排列sort(ar, ar + N, absGreater);print(ar, N);}