New Features of C ++ 11: tuple

We have used pair. pair in C ++ as a template type, which contains two data values. The two data types can be different. pair can be constructed using make_pair.

pair
 
   p = make_pair(1, "a1");
 

If multiple parameters are passed in, you need to nest pair, as shown in the following code:

# Include
 
  
# Include
  Using namespace std; int main (){//
   
    
Note: Use '>' instead of '> 'map In the nested template real parameter list.
    
     
> M; map
     
      
Temp1; temp1.insert (make_pair ("b1", "c1"); map
      
        > Temp2; temp2.insert (make_pair ("a1", temp1); m. insert (make_pair (1, temp2); map
       
         Temp3; temp3.insert (make_pair ("b2", "c2"); map
        
          > Temp4; temp4.insert (make_pair ("a2", temp3); m. insert (make_pair (2, temp4); // traverse the map
         
           >>: Const_iterator itr1; map
          
            >:: Const_iterator itr2; map
           
             : 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
            
              P = make_pair (1, "a1"); return 0 ;}
            
           
          
         
        
       
      
     
    
   
 

The above method is obviously very troublesome. The variable length parameter template was introduced in C ++ 11, so a new data type was invented: tuple, tuple is an N-tuples, and one can be input, two or more different types of data avoid the ugly practice of nesting pair. Create a tuples through make_tuple () and access the elements of the tuples through get <> ().

#include 
 
  #include 
  
   #include 
   
    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
    
      > tv;tv.push_back(make_tuple(1, "a1", "b1", "c1"));tv.push_back(make_tuple(2, "a2", "b2", "c2"));vector
     
       >::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;}