我们在C++中都用过pair.pair是一种模板类型,其中包含两个数据值,两个数据的类型可以不同.pair可以使用make_pair构造
pair<int, string> p = make_pair(1, "a1");
#include <iostream> #include <map> using namespace std; int main() { //<int, string, string, string> ,注意:在嵌套模板实参列表中应当使用‘> >’而非‘>>’ map<int, map<string, map<string, string> > > m; map<string, string> temp1; temp1.insert(make_pair("b1", "c1")); map<string, map<string, string> > temp2; temp2.insert(make_pair("a1", temp1)); m.insert(make_pair(1, temp2)); map<string, string> temp3; temp3.insert(make_pair("b2", "c2")); map<string, map<string, string> > temp4; temp4.insert(make_pair("a2", temp3)); m.insert(make_pair(2, temp4)); //遍历 map<int, map<string, map<string, string> > >::const_iterator itr1; map<string, map<string, string> >::const_iterator itr2; map<string, string>::const_iterator itr3; for (itr1=m.begin(); itr1!=m.end(); itr1++) { cout << itr1->first << " "; itr2 = (itr1->second).begin(); cout << itr2->first << " "; itr3 = (itr2->second).begin(); cout << itr3->first << " "; cout << itr3->second << endl; } pair<int, string> p = make_pair(1, "a1"); return 0; }
上面的做法明显很麻烦,在C++11中引入了变长参数模板,所以发明了新的数据类型:tuple,tuple是一个N元组,可以传入1个, 2个甚至多个不同类型的数据,避免了嵌套pair的丑陋做法,通过make_tuple()创建元组,通过get<>()来访问元组的元素
#include <iostream> #include <tuple> #include <vector> using namespace std; int main() { auto t1 = make_tuple(1, "a1", "b1", "c1"); cout << get<0>(t1) << " "; cout << get<1>(t1) << " "; cout << get<2>(t1) << " "; cout << get<3>(t1) << " "; cout << endl; vector<tuple<int, string, string, string> > tv; tv.push_back(make_tuple(1, "a1", "b1", "c1")); tv.push_back(make_tuple(2, "a2", "b2", "c2")); vector<tuple<int, string, string, string> >::iterator itr; for (itr=tv.begin(); itr!=tv.end(); itr++) { cout << get<0>(*itr) << " "; cout << get<1>(*itr) << " "; cout << get<2>(*itr) << " "; cout << get<3>(*itr) << endl; } return 0; }
C++11 新特性之 tuple,布布扣,bubuko.com
原文:http://blog.csdn.net/aspnet_lyc/article/details/30980465