一個結構體，這個結構體提供了融合2個對象變為一個對象的能力；

template<class Type1, class Type2>struct pair {typedef Type1 first_type;typedef Type2 second_typeType1 first;Type2 second;pair( );pair(const Type1& __Val1, const Type2& __Val2);template<class Other1, class Other2>pair(const pair<Other1, Other2>& _Right);void swap(pair<Type1, Type2>& _Right)};

下面給出官方的栗子：

運行截圖如下：

源碼如下：

#include <utility> #include <map> #include <iomanip> #include <iostream>int main( ) {using namespace std;// Using the constructor to declare and initialize a pairpair <int, double> p1 ( 10, 1.1e-2 );// Compare using the helper function to declare and initialize a pairpair <int, double> p2;p2 = make_pair ( 10, 2.22e-1 );// Making a copy of a pairpair <int, double> p3 ( p1 );cout.precision ( 3 );cout << "The pair p1 is: ( " << p1.first << ", " << p1.second << " )." << endl;cout << "The pair p2 is: ( " << p2.first << ", " << p2.second << " )." << endl;cout << "The pair p3 is: ( " << p3.first << ", " << p3.second << " )." << endl;// Using a pair for a map elementmap <int, int> m1;map <int, int>::iterator m1_Iter;typedef pair <int, int> Map_Int_Pair;m1.insert ( Map_Int_Pair ( 1, 10 ) );m1.insert ( Map_Int_Pair ( 2, 20 ) );m1.insert ( Map_Int_Pair ( 3, 30 ) );cout << "The element pairs of the map m1 are:";for ( m1_Iter = m1.begin( ); m1_Iter != m1.end( ); m1_Iter++ )cout << " ( " << m1_Iter -> first << ", "<< m1_Iter -> second << " )";cout << "." << endl;// Using pair as a return type for a functionpair< map<int,int>::iterator, bool > pr1, pr2;pr1 = m1.insert ( Map_Int_Pair ( 4, 40 ) );pr2 = m1.insert ( Map_Int_Pair (1, 10 ) );if( pr1.second == true ){cout << "The element (4,40) was inserted successfully in m1."<< endl;}else {cout << "The element with a key value of\n"<< " ( (pr1.first) -> first ) = " << ( pr1.first ) -> first << " is already in m1,\n so the insertion failed." << endl;}if( pr2.second == true ){cout << "The element (1,10) was inserted successfully in m1."<< endl;}else {cout << "The element with a key value of\n"<< " ( (pr2.first) -> first ) = " << ( pr2.first ) -> first << " is already in m1,\n so the insertion failed." << endl;}getchar(); }

從這個例子可以看出，pair一般與map搭配使用，難怪看大佬敲代碼，就會用pair進行操作！

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