Sequence Containers in C++

By Shanigaram Mahesh

In this tutorial, we will learn about sequence containers in C++. What is the sequence containers and why we use it in?

What is Sequence Containers in C++

A sequence is a container that stores a finite set of objects of the same type in a linear organization. An array of names is a sequence. You would use one of the three sequence types–std::vector, std ::list, or std::deque –for a particular application depending on its retrieval requirements.

The std :: vector Class in sequence containers

An std :: vector is a sequence you can access at random. You can append entries to and remove entries from the end of the std ::vector without the undue overhead. Insertion and deletion at the beginning or in the middle of the std :: vector takes more time because they involve shifting the remaining entries to make room or to close up the deleted object space. An std :: vector is an array of contiguous objects with an instance counter or pointer to indicate the end of the container. Random access is a matter of using a subscript operation.

The std :: list Class

A std:: list is a sequence you can access bidirectionally. A std:: list enables you to perform inserts and deletion anywhere without undue performance penalties. Random access is simulated by forward or backward iteration to the target object. An  std:: list consists of non-contiguous objects linked together with forward and backward pointers.

The std ::deque Class

An std:: deque is like an std:: vector except for an std:: deque allows fast inserts and deletes at the beginning, as well as the end, of the container. Random inserts and deletes take more time.

 

#include<iostream>
#include<iomanip>
#include<vector>
#include<algorithm>
using namespace std;
int main()
{
int dim;
std::cout<<"How many integers? ";
std::cin>>dim;
// --a vector of integers
std::vector<int> vct;
// -- insert values into the vector
for( int i=0;i<dim;i++)
vct.insert(vct.end(),std:: rand());
std::cout<<"\n -- unsorted --";
std::vector<int>::iterator iter;
//redeclaration
for(i=0, iter=vct.begin();iter<vct.end(); iter++,i++)
{
if((i%4)==0)
std::cout<<"\n";
std::cout<<std::setw(8)<<*iter;
}
// --sort the array with the std sort algorithm
std::sort(vct.begin(), vct.end());
std::cout<<"\n --sorted --";
for(i=0,iter =vct.begin(); iter <vct.end(); iter++,i++)
{
if((i%4)==0)
std::cout<<"\n";
std::cout<<std::setw(8)<<*iter;
}
}

Output from program

how many integers? 8
-- unsorted --
41    18467     6334    26500
19169     15724   11478     29358
-- sorted --
41    6334    11478  15724
18467   19169   26500  29358

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