How to use deque::front and deque::back STL functions in Visual C++

View products that this article applies to.

This article was previously published under Q156760

SUMMARY

The sample code below illustrates how to use the deque::front and deque::back STL functions for the deque container class in Visual C++.

Back to the top

MORE INFORMATION

Required header

< deque>

Back to the top

Prototype

   reference front();
   const_reference front() const;

   reference back();
   const_reference back() const;

Note The class/parameter names in the prototype may not match the version in the header file. Some have been modified to improve readability.

Back to the top

Description

The member function front() returns a reference to the first element of the controlled sequence, which must be non-empty.

The member function back() returns a reference to the last element of the controlled sequence, which must be non-empty.

Back to the top

Sample code

Note In the first line of the sample code section, /GX is equivalent to /EHsc in VC++ .NET and is set by default.

   ////////////////////////////////////////////////////////////////////// 
   // 
   // Compile options needed: -GX
   // 
   // deque.cpp :
   // 
   // Functions:
   // 
   //    front()
   // 
   //    back()
   // 
   // Written by Bobby Mattappally
   // of Microsoft Product Support Services,
   // Copyright (c) 1996 Microsoft Corporation. All rights reserved.
   ////////////////////////////////////////////////////////////////////// 

   /* Compile options needed:-GX
   */ 
   #include <iostream>
   #include <deque>
  
#if _MSC_VER > 1020   // if VC++ version is > 4.2
   using namespace std;  // std c++ libs implemented in std
   #endif

   typedef deque<char, allocator<char> >  CHARDEQUE;
   void print_contents (CHARDEQUE  deque, char*);

   void main()
   {
       //create a  with  A, B, C and D
       CHARDEQUE  a;
       a.push_back('A');
       a.push_back('B');
       a.push_back('C');
       a.push_back('D');

       //print out the contents
       print_contents (a,"a");

       cout <<"The first element of a is " <<a.front() <<endl;

       cout <<"The last element of a is " <<a.back() <<endl;

       //now let us modify the first and last elements
       //using reference ,front() and back()

       CHARDEQUE::reference reffront=a.front();
       CHARDEQUE::reference refback=a.back();

       reffront='X';
       refback='Y';

        //print out the contents
        print_contents (a,"a");

       }

   //function to print the contents of deque
   void print_contents (CHARDEQUE  deque, char *name)
   {
       CHARDEQUE::iterator pdeque;

       cout <<"The contents of "<< name <<" : ";

           for(pdeque = deque.begin();
           pdeque != deque.end();
           pdeque++)
       {
           cout << *pdeque <<" " ;
       }
           cout<<endl;

   }

Program output is:

   The contents of a : A B C D

   The first element of a is A

   The last element of a is D

   The contents of a : X B C Y

Back to the top

REFERENCES

For the same topic about deque::front and deque::back, visit the following MSDN Web site: http://msdn.microsoft.com/en-us/library/0w4bdc19.aspx (http://msdn.microsoft.com/en-us/library/0w4bdc19.aspx)

Back to the top