map::rbegin

傳回所定址的 Iterator 在一個反向的對應的第一個項目。

const_reverse_iterator rbegin( ) const; 
reverse_iterator rbegin( );

傳回值

解決反向雙向 Iterator 的說明一個反向的對應的第一個項目或功能在資料 unreversed 對應的最後一個項目。

備註

無效 啟動 搭配對應，rbegin 搭配一個反向的對應。

如果 rbegin 的傳回值指派給 const_reverse_iterator，則無法修改對應物件。 如果 rbegin 的傳回值指派給 reverse_iterator，則可以修改對應物件。

rbegin 可以用來在對應至之後重複。

範例

// map_rbegin.cpp
// compile with: /EHsc
#include <map>
#include <iostream>

int main( )
{
   using namespace std;   
   map <int, int> m1;

   map <int, int> :: iterator m1_Iter;
   map <int, int> :: reverse_iterator m1_rIter;
   map <int, int> :: const_reverse_iterator m1_crIter;
   typedef pair <int, int> Int_Pair;

   m1.insert ( Int_Pair ( 1, 10 ) );
   m1.insert ( Int_Pair ( 2, 20 ) );
   m1.insert ( Int_Pair ( 3, 30 ) );

   m1_rIter = m1.rbegin( );
   cout << "The first element of the reversed map m1 is "
        << m1_rIter -> first << "." << endl;

   // begin can be used to start an iteration 
   // through a map in a forward order
   cout << "The map is: ";
   for ( m1_Iter = m1.begin( ) ; m1_Iter != m1.end( ); m1_Iter++)
      cout << m1_Iter -> first << " ";
      cout << "." << endl;

   // rbegin can be used to start an iteration 
   // through a map in a reverse order
   cout << "The reversed map is: ";
   for ( m1_rIter = m1.rbegin( ) ; m1_rIter != m1.rend( ); m1_rIter++)
      cout << m1_rIter -> first << " ";
      cout << "." << endl;

   // A map element can be erased by dereferencing to its key 
   m1_rIter = m1.rbegin( );
   m1.erase ( m1_rIter -> first );

   m1_rIter = m1.rbegin( );
   cout << "After the erasure, the first element "
        << "in the reversed map is "
        << m1_rIter -> first << "." << endl;
}

需求

標題: <map>

命名空間: std

請參閱

參考

map Class

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