//c++ pair和tuple的操作 //1.初始化见函数Init() tupleTopair() class Foo; //2.pair的输出 见print() //3.pair关于tuple的接口 见函数 tupleInpair() //4.make_pair() 见mp() //5.pair c++11 注意点 pair<>里类型若只有一个 //nonconstant copy函数编译器将报错
#include<iostream> #include<tuple> using namespace std; void Init() { //初始化 //常规初始化 pair<int, double> p1(4, 4.22);//... //用tuple初始化//更多见函数tupleTopair和class Foo pair<int, double> p2(piecewise_construct, make_tuple(2), make_tuple(2.33)); } class Foo { public: Foo(tuple<int, double>) { cout << "Foo::Foo(tuple)" << endl; } template<typename ...Args> Foo(Args...args) { cout << "Foo::Foo(args...)" << endl; } }; void tupleTopair() { tuple<int, double> t(4, 4.33); pair<int, Foo> p1(43, t);//调用Foo(tuple<int,double>) //因Class pair<>提供逐块构造函数则指明piecewise_construct会调用 //Foo(Arg...args) pair<int, Foo> p2(piecewise_construct, make_tuple(43), make_tuple(45, 37)); } template<typename T1,typename T2> ostream& operator <<(ostream& os, const pair<T1, T2>& p) { return os << "[" << p.first << "," << p.second << "]"; } void print() { pair<int, double> p(2, 3.444); cout << p; } void tupleInpair() { pair<int, double> p(2, 4.333); //用get<0>(p) get<1>(p)得到p.first p.second cout << get<0>(p) << ends << get<1>(p) << endl; //得到类型的个数 cout << tuple_size<pair<int, double>>::value << endl; //得到特定位置的类型 tuple_element<0, pair<int, double>>::type a = 4; cout << a << endl; //使用tuple的tie()接口抽取pair的value double d; tie(ignore, d) = p; cout << d << endl; } void mp() { int a = 3; int b = 4; auto p1 = make_pair(a, b); ++a;//a = 4; --b;//b = 3; cout << p1.first << ends << p1.second << endl; auto p2 = make_pair(ref(a), ref(b));//a = 4; b = 3; --a; ++b; //a = 3 b = 4; cout << p2.first << ends << p2.second << endl; } int main() { //tupleTopair(); //print(); //tupleInpair(); mp(); system("pause"); return 0; }