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21.2.1 vector Sequence Container
• Declarations
– std::vector <type> v;
• type: int, float, etc.
• Iterators
– std::vector<type>::const_iterator iterVar;
• const_iterator cannot modify elements
– std::vector<type>::reverse_iterator iterVar;
• Visits elements in reverse order (end to beginning)
• Use rbegin to get starting point
• Use rend to get ending point
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21.2.1 vector Sequence Container
• vector functions
– v.push_back(value)
• Add element to end (found in all sequence containers).
– v.size()
• Current size of vector
– v.capacity()
• How much vector can hold before reallocating memory
• Reallocation doubles size
– vector<type> v(a, a + SIZE)
• Creates vector v with elements from array a up to (not including)
a + SIZE
2003 Prentice Hall, Inc. All rights reserved.
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21.2.1 vector Sequence Container
• vector functions
– v.insert(iterator, value )
• Inserts value before location of iterator
– v.insert(iterator, array , array + SIZE)
• Inserts array elements (up to, but not including array + SIZE) into
vector
– v.erase( iterator )
• Remove element from container
– v.erase( iter1, iter2 )
• Remove elements starting from iter1 and up to (not including)
iter2
– v.clear()
• Erases entire container
2003 Prentice Hall, Inc. All rights reserved.
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21.2.1 vector Sequence Container
• vector functions operations
– v.front(), v.back()
• Return first and last element
– v.[elementNumber] = value;
• Assign value to an element
– v.at[elementNumber] = value;
• As above, with range checking
• out_of_bounds exception
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21.2.1 vector Sequence Container
• ostream_iterator
– std::ostream_iterator< type >
Name( outputStream, separator );
• type: outputs values of a certain type
• outputStream: iterator output location
• separator: character separating outputs
• Example
– std::ostream_iterator< int > output( cout, " " );
– std::copy( iterator1, iterator2, output );
• Copies elements from iterator1 up to (not including)
iterator2 to output, an ostream_iterator
2003 Prentice Hall, Inc. All rights reserved.
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// Fig. 21.14: fig21_14.cpp
// Demonstrating standard library vector class template.
#include <iostream>
Outline
fig21_14.cpp
(1 of 3)
using std::cout;
using std::cin;
using std::endl;
#include <vector>
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// vector class-template definition
// prototype for function template printVector
template < class T >
void printVector( const std::vector< T > &integers2 );
int main()
{
Create a
const int SIZE = 6;
int array[ SIZE ] = { 1, 2, 3, 4, 5, 6 };
std::vector< int > integers;
cout <<
<<
<<
<<
vector of ints.
Call member functions.
"The initial size of integers is: "
integers.size()
"\nThe initial capacity of integers is: "
integers.capacity();
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All rights reserved.
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// function push_back
integers.push_back( 2
integers.push_back( 3
integers.push_back( 4
is in every sequence collection
);
);
);
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Add elements to end of Outline
vector using push_back.
cout << "\nThe size of integers is: " << integers.size()
<< "\nThe capacity of integers is: "
<< integers.capacity();
fig21_14.cpp
(2 of 3)
cout << "\n\nOutput array using pointer notation: ";
for ( int *ptr = array; ptr != array + SIZE; ++ptr )
cout << *ptr << ' ';
cout << "\nOutput vector using iterator notation: ";
printVector( integers );
cout << "\nReversed contents of vector integers: ";
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All rights reserved.
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std::vector< int >::reverse_iterator reverseIterator;
for ( reverseIterator = integers.rbegin();
reverseIterator!= integers.rend();
++reverseIterator )
cout << *reverseIterator << ' ';
Outline
Walk through vector
fig21_14.cpp
backwards using (3
a of 3)
reverse_iterator.
cout << endl;
return 0;
} // end main
// function template for outputting vector elements
template < class T >
void printVector( const std::vector< T > &integers2 )
{
std::vector< T >::const_iterator constIterator;
Template function to walk
through vector forwards.
for ( constIterator = integers2.begin();
constIterator != integers2.end();
constIterator++ )
cout << *constIterator << ' ';
} // end function printVector
2003 Prentice Hall, Inc.
All rights reserved.
The
The
The
The
initial size of v is: 0
initial capacity of v is: 0
size of v is: 3
capacity of v is: 4
Contents of array a using pointer notation: 1 2 3 4 5 6
Contents of vector v using iterator notation: 2 3 4
Reversed contents of vector v: 4 3 2
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Outline
fig21_14.cpp
output (1 of 1)
2003 Prentice Hall, Inc.
All rights reserved.
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// Fig. 21.15: fig21_15.cpp
// Testing Standard Library vector class template
// element-manipulation functions.
#include <iostream>
Outline
fig21_15.cpp
(1 of 3)
using std::cout;
using std::endl;
#include <vector>
#include <algorithm>
// vector class-template definition
// copy algorithm
int main()
{
const int SIZE = 6;
int array[ SIZE ] = { 1, 2, 3, 4, 5, 6 };
std::vector< int > integers( array, array + SIZE );
std::ostream_iterator< int > output( cout, " " );
Create vector (initialized
using an array) and
ostream_iterator.
Copy range of iterators to output
(ostream_iterator).
cout << "Vector integers contains: ";
std::copy( integers.begin(), integers.end(), output );
cout << "\nFirst element of integers: " << integers.front()
<< "\nLast element of integers: " << integers.back();
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integers[ 0 ] = 7;
integers.at( 2 ) = 10;
// set first element to 7
// set element at position 2 to 10
// insert 22 as 2nd element
integers.insert( integers.begin() + 1, 22 );
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Outline
More vector member
fig21_15.cpp
functions.
(2 of 3)
cout << "\n\nContents of vector integers after changes: ";
std::copy( integers.begin(), integers.end(), output );
// access out-of-range element
try {
integers.at( 100 ) = 777;
at has range checking, and
can throw an exception.
} // end try
// catch out_of_range exception
catch ( std::out_of_range outOfRange ) {
cout << "\n\nException: " << outOfRange.what();
} // end catch
// erase first element
integers.erase( integers.begin() );
cout << "\n\nVector integers after erasing first element: ";
std::copy( integers.begin(), integers.end(), output );
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// erase remaining elements
integers.erase( integers.begin(), integers.end() );
cout << "\nAfter erasing all elements, vector integers "
<< ( integers.empty() ? "is" : "is not" ) << " empty";
// insert elements from array
integers.insert( integers.begin(), array, array + SIZE );
cout << "\n\nContents of vector integers before clear: ";
std::copy( integers.begin(), integers.end(), output );
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Outline
fig21_15.cpp
(3 of 3)
// empty integers; clear calls erase to empty a collection
integers.clear();
cout << "\nAfter clear, vector integers "
<< ( integers.empty() ? "is" : "is not" ) << " empty";
cout << endl;
return 0;
} // end main
2003 Prentice Hall, Inc.
All rights reserved.
Vector integers contains: 1 2 3 4 5 6
First element of integers: 1
Last element of integers: 6
Contents of vector integers after changes: 7 22 2 10 4 5 6
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Outline
fig21_15.cpp
output (1 of 1)
Exception: invalid vector<T> subscript
Vector integers after erasing first element: 22 2 10 4 5 6
After erasing all elements, vector integers is empty
Contents of vector integers before clear: 1 2 3 4 5 6
After clear, vector integers is empty
2003 Prentice Hall, Inc.
All rights reserved.
