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MODULE 27

THE STL CONTAINER PART 2

vector, deque

My Training Period: xx hours

Program examples compiled using VC++7.0/.Net, win32 empty console mode application. g++ examples given at the end of this Module. The source code for this tutorial is available in C++ STL Container source code.

C++ STL container abilities that should be acquired:

▪ Able to understand the containers.

▪ Able to understand sequence and associative containers.

▪ Able to understand and use vector sequence container.

▪ Able to understand and use deque sequence container.

The Standard Template Library (STL) is a generic library that provides solutions to managing collections of data with an efficient algorithm.
The STL provides a collection of classes that meet different kind of tasks, with algorithms that operate on the classes. STL components are templates, as you have learned in Module 24, it can be used for arbitrary data types.
Furthermore, STL also provides a framework for other collection of user defined classes or algorithms. The traditional programming such as dynamic arrays, linked lists, binary trees, search algorithms and other data structures routines can be implemented using STL more efficiently and easily.
To easily understand this topic, you should have good understanding of the traditional arrays data type and operations that can be done on arrays elements such as comparison, sorting, deletion, modification, insertion etc. and as well as templates.

What we have in this page?

vector constructors program example
vector, assign() program example
vector, at() program example
vector, back() and front() program example
vector, begin() program example
vector, capacity() and size() program example
vector, clear(), empty() and size() program example
vector, begin(), end() program example
vector, erase(), begin() and end() program example
vector, insert(), begin(), end() program example

The following section demonstrates the program examples using the member functions and the typedefs
Vector constructor, constructs a vector of a specific size or with elements of a specific value or with a specific allocator or as a copy of all or part of some other vector.
All constructors store an allocator object and initialize the vector.

// vector constructors

#include <vector>

#include <iostream>

using namespace std;

int main()

{

vector <int>::iterator vec0Iter, vec1Iter, vec2Iter, vec3Iter, vec4Iter, vec5Iter;

// create an empty vector vec0

vector <int> vec0;

// create a vector vec1 with 10 elements of default value 0

vector <int> vec1(10);

// create a vector vec2 with 7 elements of value 13

vector <int> vec2(7, 13);

// create a vector vec3 with 5 elements of value 3 and with the allocator of vector vec2

vector <int> vec3(5, 3, vec2.get_allocator());

// vector vec4, a copy of vector vec2

vector <int> vec4(vec2);

// create a vector vec5 by copying the range of vec4[_First, _Last)

vector <int> vec5(vec4.begin() + 1, vec4.begin() + 3);

cout<<"Operation: vector <int> vec0\n";

cout<<"vec0 data: ";

for(vec0Iter = vec0.begin(); vec0Iter != vec0.end(); vec0Iter++)

cout<<" "<<*vec0Iter;

cout<<endl;

cout<<"\nOperation: vector <int> vec1(10)\n";

cout<<"vec1 data: ";

for(vec1Iter = vec1.begin(); vec1Iter != vec1.end(); vec1Iter++)

cout<<" "<<*vec1Iter;

cout<<endl;

cout<<"\nOperation: vector <int> vec2(7, 13)\n";

cout<<"vec2 data: ";

for(vec2Iter = vec2.begin(); vec2Iter != vec2.end(); vec2Iter++)

cout<<" "<<*vec2Iter;

cout<<endl;

cout<<"\nOperation: vector <int> vec3(5, 3, vec2.get_allocator())\n";

cout<<"vec3 data: ";

for(vec3Iter = vec3.begin(); vec3Iter != vec3.end(); vec3Iter++)

cout<<" "<<*vec3Iter;

cout<<endl;

cout<<"\nOperation: vector <int> vec4(vec2)\n";

cout<<"vec4 data: ";

for(vec4Iter = vec4.begin(); vec4Iter != vec4.end(); vec4Iter++)

cout<<" "<<*vec4Iter;

cout<<endl;

cout<<"\nOperation: vector <int> vec5(vec4.begin()+1, vec4.begin()+3)\n";

cout<<"vec5 data: ";

for(vec5Iter = vec5.begin(); vec5Iter != vec5.end(); vec5Iter++)

cout<<" "<<*vec5Iter;

cout<<endl;

return 0;

}

Output:

C++ STL Container vector constructor

After erasing any existing elements in a vector, assign() either inserts a specified range of elements from the original vector into a vector or inserts copies of a new element of a specified value into a vector.

// vector, assign()

#include <vector>

#include <iostream>

using namespace std;

int main()

{

vector <int> vec2;

vector <int>::iterator Iter;

vec2.push_back(1);

vec2.push_back(5);

vec2.push_back(3);

vec2.push_back(4);

vec2.push_back(5);

vec2.push_back(3);

vec2.push_back(7);

vec2.push_back(8);

vec2.push_back(4);

cout<<"Operation: vec2.begin() and vec2.end()"<<endl;

cout<<"vec2 data: ";

for(Iter = vec2.begin(); Iter != vec2.end(); Iter++)

cout<<*Iter<<" ";

cout<<"\n\n";

cout<<"Operation: vec2.assign(vec2.begin()+1, vec2.begin()+3)"<<endl;

vec2.assign(vec2.begin()+2, vec2.begin()+8);

cout<<"vec2 data: ";

for(Iter = vec2.begin(); Iter != vec2.end(); Iter++)

cout<<*Iter<<" ";

cout<<"\n\n";

cout<<"Operation: vec2.assign(5, 7)"<<endl;

vec2.assign(5, 7);

cout<<"vec2 data: ";

for(Iter = vec2.begin(); Iter != vec2.end(); Iter++)

cout<<*Iter<<" ";

cout<<endl;

return 0;

}

Output:

C++ STL Container vector assign()

The return value is a reference to the element subscripted in the argument. If _Off is greater than the size of the vector, at() throws an exception.
If the return value of at() is assigned to a const_reference, the vector object cannot be modified. If the return value of at() is assigned to a reference, the vector object can be modified.

// vector, at()

#include <vector>

#include <iostream>

using namespace std;

int main()

{

vector <int> vec1;

vec1.push_back(1);

vec1.push_back(7);

vec1.push_back(4);

vec1.push_back(3);

// print all elements separated by a space

cout<<"The vec1 data: ";

for(int i=0; i<vec1.size(); ++i)

cout<<vec1[i]<<' ';

cout<<"\n\nOperation: vec1.at(position)";

const int &x = vec1.at(1);

int &y = vec1.at(3);

int &z = vec1.at(0);

cout<<"\nThe 2nd element is "<<x<<endl;

cout<<"The 4th element is "<<y<<endl;

cout<<"The 1st element is "<<z<<endl;

return 0;

}

Output:

C++ STL Container vector at()

For back(), the return value is the last element of the vector. If the vector is empty, the return value is undefined.
If the return value of back() is assigned to a const_reference, the vector object cannot be modified. If the return value of back() is assigned to a reference, the vector object can be modified.
For front(), the return value is a reference to the first element in the vector object. If the vector is empty, the return is undefined.
If the return value of front() is assigned to a const_reference, the vector object cannot be modified. If the return value of front() is assigned to a reference, the vector object can be modified.

// vector, back() and front()

#include <vector>

#include <iostream>

using namespace std;

int main()

{

vector <int> vec1, vec2;

vec1.push_back(12);

vec1.push_back(10);

vec1.push_back(7);

// print all elements separated by a space

cout<<"vec1 data: ";

for(int i=0; i<vec1.size(); ++i)

cout<<vec1[i]<<' ';

cout<<endl;

int& x = vec1.back();

const int& y = vec1.front();

cout<<"\nOperation: x = vec1.back()\n";

cout<<"The last integer of vec1 is "<<x<<endl;

cout<<"Operation: y = vec1.front()\n";

cout<<"The 1st integer of vec1 is "<<y<<endl;

return 0;

}

Output:

C++ STL Container vector back() and front()

The return value is a random-access iterator addressing the first element in the vector or to the location succeeding an empty vector.
If the return value of begin() is assigned to a const_iterator, the vector object cannot be modified. If the return value of begin() is assigned to an iterator, the vector object can be modified.

// vector, begin()

#include <vector>

#include <iostream>

using namespace std;

int main()

{

vector <int> vec1;

vector <int>::iterator vec1_Iter;

vec1.push_back(21);

vec1.push_back(12);

vec1.push_back(32);

cout<<"vec1 data: ";

for(int i=0; i<vec1.size(); ++i)

cout<<vec1[i]<<' ';

cout<<endl;

cout<<"\nOperation: vec1.begin()\n";

vec1_Iter = vec1.begin();

cout<<"The first element of vec1 is "<<*vec1_Iter<<endl;

cout<<"\nOperation: *vec1_Iter = 10\n";

*vec1_Iter = 10;

cout<<"new vec1 data: ";

for(i=0; i<vec1.size(); ++i)

cout<<vec1[i]<<' ';

cout<<endl;

cout<<"Operation: vec1.begin()\n";

vec1_Iter = vec1.begin();

cout<<"The first element of vec1 is now "<<*vec1_Iter<<endl;

return 0;

}

Output:

C++ STL Container vector begin()

The return value is the current length of storage allocated for the vector.
The member function resize() will be more efficient if sufficient memory is allocated to accommodate it. Use a member function reserve() to specify the amount of memory allocated.

// vector, capacity() and size()

#include <vector>

#include <iostream>

using namespace std;

int main()

{

vector <int> vec1;

vec1.push_back(3);

vec1.push_back(1);

vec1.push_back(6);

cout<<"vec1 data: ";

for(int i=0; i<vec1.size(); ++i)

cout<<vec1[i]<<' ';

cout<<endl;

cout<<"Operation: vec1.capacity()\n";

cout<<"The length of storage allocated is "<<vec1.capacity()<<"."<<endl;

vec1.push_back(10);

vec1.push_back(12);

vec1.push_back(4);

cout<<"\nnew vec1 data: ";

for(i=0; i<vec1.size(); ++i)

cout<<vec1[i]<<' ';

cout<<endl;

cout<<"The length of storage allocated is now "<<vec1.capacity()<<"."<<endl;

return 0;

}

Output:

C++ STL Container vector capacity()

For empty(), the return value is true if the vector is empty; false if the vector is not empty.

// vector, clear(), empty() and size()

#include <vector>

#include <iostream>

using namespace std;

int main()

{

vector <int> vec1;

vec1.push_back(10);

vec1.push_back(20);

vec1.push_back(30);

cout<<"vec1 data: ";

for(int i=0; i<vec1.size(); ++i)

cout<<vec1[i]<<' ';

cout<<endl;

cout<<"The size of vec1 is "<<vec1.size()<<endl;

cout<<"\nOperation: vec1.empty()"<<endl;

if(vec1.empty())

cout<<"vec1 is empty"<<endl;

else

cout<<"vec1 is not empty"<<endl;

cout<<"\nOperation: vec1.clear()"<<endl;

vec1.clear();

cout<<"The size of vec1 after clearing is "<<vec1.size()<<endl;

cout<<"\nOperation: vec1.empty()"<<endl;

if(vec1.empty())

cout<<"vec1 is empty"<<endl;

else

cout<<"vec1 is not empty"<<endl;

return 0;

}

Output:

-----------------------------------------------------------------------------------------

C++ STL Container vector clear() and empty()

For end(), the return value is a pointer to the end of the vector object. If the vector is empty, the result is undefined.
If the return value of end() is assigned to a variable of type const_iterator, the vector object cannot be modified. If the return value of end() is assigned to a variable of type iterator, the vector object can be modified.

// vector, begin(), end()

#include <vector>

#include <iostream>

int main( )

{

using namespace std;

vector <int> vec1;

vector <int>::iterator vec1_Iter;

vec1.push_back(9);

vec1.push_back(2);

vec1.push_back(7);

vec1.push_back(3);

cout<<"Operation: vec1.begin() and vec1.end()"<<endl;

cout<<"vec1 data: ";

for(vec1_Iter = vec1.begin(); vec1_Iter != vec1.end(); vec1_Iter++)

cout<<*vec1_Iter<<' ';

cout<<endl;

return 0;

}

Output:

C++ STL Container vector begin() and end()

The return value for erase() is an iterator that designates the first element remaining beyond any elements removed, or a pointer to the end of the vector if no such element exists.

// vector, erase(), begin() and end()

#include <vector>

#include <iostream>

using namespace std;

int main()

{

vector <int> vec1;

vector <int>::iterator Iter;

vec1.push_back(3);

vec1.push_back(7);

vec1.push_back(22);

vec1.push_back(5);

vec1.push_back(12);

vec1.push_back(17);

cout<<"Original vec1 data: ";

for(Iter = vec1.begin(); Iter != vec1.end(); Iter++)

cout<<" "<<*Iter;

cout<<endl;

cout<<"\nOperation: erase(vec1.begin()"<<endl;

vec1.erase(vec1.begin());

cout<<"New vec1 data: ";

for(Iter = vec1.begin(); Iter != vec1.end(); Iter++)

cout<<" "<<*Iter;

cout<<endl;

cout<<"\nOperation: vec1.erase(vec1.begin()+1, vec1.begin()+3)"<<endl;

vec1.erase(vec1.begin() + 1, vec1.begin() + 3);

cout<<"New vec1 data: ";

for(Iter = vec1.begin(); Iter != vec1.end(); Iter++)

cout<<" "<<*Iter;

cout<<endl;

return 0;

}

Output:

C++ STL Container vector erase() and begin()

The return value is the first insert() function returns an iterator that point to the position where the new element was inserted into the vector.

// vector, insert(), begin(), end()

#include <vector>

#include <iostream>

using namespace std;

int main()

{

vector <int> vec1;

vector <int>::iterator Iter;

vec1.push_back(12);

vec1.push_back(100);

vec1.push_back(9);

vec1.push_back(21);

cout<<"Original vec1 data: ";

for(Iter = vec1.begin(); Iter != vec1.end(); Iter++)

cout<<" "<<*Iter;

cout<<endl;

cout<<"\nOperation: vec1.insert(vec1.begin()+1, 17)"<<endl;

vec1.insert(vec1.begin()+1, 17);

cout<<"New vec1 data: ";

for(Iter = vec1.begin(); Iter != vec1.end(); Iter++)

cout<<" "<<*Iter;

cout<<endl;

cout<<"\nOperation: vec1.insert(vec1.begin()+2, 3, 24)"<<endl;

vec1.insert(vec1.begin()+2, 3, 24);

cout<<"New vec1 data: ";

for(Iter = vec1.begin(); Iter != vec1.end(); Iter++)

cout<<" "<<*Iter;

cout<<endl;

cout<<"\nOperation: vec1.insert(vec1.begin()+1, \n"

" vec1.begin()+2, vec1.begin()+4)"<<endl;

vec1.insert(vec1.begin()+1, vec1.begin()+2, vec1.begin()+4);

cout<<"New vec1 data: ";

for(Iter = vec1.begin(); Iter != vec1.end(); Iter++)

cout<<" "<<*Iter;

cout<<endl;

return 0;

}

Output:

C++ STL Container vector insert()

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Further C++ STL container related reading:

The source code for this tutorial is available in C++ STL Container source code.
A complete C & C++ Standard Library documentation that includes STL.
Check the best selling C / C++ books at Amazon.com.

|< C++ STL Container 1 | Main | C++ STL Container 3 >| Site Index | Download |

|< C++ STL Container 1 | Main | C++ STL Container 3 >| Site Index | Download |

MODULE 27

THE STL CONTAINER PART 2

vector, deque

My Training Period: xx hours

C++ STL container abilities that should be acquired:

▪ Able to understand the containers.

▪ Able to understand sequence and associative containers.

▪ Able to understand and use vector sequence container.

▪ Able to understand and use deque sequence container.

What we have in this page?

vector constructors program example

vector, assign() program example

vector, at() program example

vector, back() and front() program example

vector, begin() program example

vector, capacity() and size() program example

vector, clear(), empty() and size() program example

vector, begin(), end() program example

vector, erase(), begin() and end() program example

vector, insert(), begin(), end() program example

Output:

Output:

Output:

Output:

Output:

Output:

Output:

// vector, begin(), end()

#include <vector>

#include <iostream>

int main( )

{

using namespace std;

vector <int> vec1;

vector <int>::iterator vec1_Iter;

vec1.push_back(9);

vec1.push_back(2);

vec1.push_back(7);

vec1.push_back(3);

cout<<"Operation: vec1.begin() and vec1.end()"<<endl;

cout<<"vec1 data: ";

for(vec1_Iter = vec1.begin(); vec1_Iter != vec1.end(); vec1_Iter++)

cout<<*vec1_Iter<<' ';

cout<<endl;

return 0;

}

Output:

Output:

Output:

Further C++ STL container related reading:

|< C++ STL Container 1 | Main | C++ STL Container 3 >| Site Index | Download |

C++ STL Container Classes: Part 1 | Part 2 | Part 3 | Part 4 | Part 5 | Part 6 | Part 7 | Part 8 | Part 9 | Part 10 | Part 11