C++/STL Algorithms Modifying sequence operations/copy — различия между версиями
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Версия 14:21, 25 мая 2010
Содержание
- 1 Beginning and Ending Iterators of C-Style Arrays
- 2 Copy all letters three elements behind the "f"
- 3 Copy and insert list
- 4 Copy istream_iterator to ostream_iterator
- 5 Copy vector and list
- 6 Display all elements in a vector
- 7 Displaying a Container"s Elements on the Standard Output with copy function
- 8 Print all elements in a list with copy function
- 9 Use copy function to print all elements in a deque
- 10 Use copy to copy elements in one container to another container
- 11 Use copy to copy elements of one container into another container in reverse order
- 12 Use copy to fill values to an array
- 13 Use copy to output all elements in a container
- 14 Use std::copy to print all elements in a set
- 15 Use the copy algorithms: Shift the contents of vector1 left by 4 positions
- 16 Use the generic copy to duplicate vectors
Beginning and Ending Iterators of C-Style Arrays
#include <algorithm>
#include <iostream>
#include <iterator>
using namespace std;
int main( )
{
const int num_costs = 4;
const float cost[num_costs] = { 11.11, 22.22, 33.33, 44.44 };
copy( cost, cost + num_costs,ostream_iterator<float>( cout, " " ) );
const char* fruit[] = { "A", "B", "C" };
copy( fruit, fruit + sizeof( fruit ) / sizeof( fruit[0] ),
ostream_iterator<const char*>( cout, " " ) );
int year[] = { 2001, 2002, 2003, 2004, 2005 };
const int num_years = sizeof( year ) / sizeof( year[0] );
copy( year, year + num_years,ostream_iterator<int>( cout, " " ) );
sort( year, year + num_years );
copy( year, year + num_years,ostream_iterator<int>( cout, " " ) );
reverse( year, year + num_years );
copy( year, year + num_years,ostream_iterator<int>( cout, " " ) );
}
Copy all letters three elements behind the "f"
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
using namespace std;
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << " ";
}
std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
* - fill values from first to last into the collection
* - NOTE: NO half-open range
*/
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
for (int i=first; i<=last; ++i) {
coll.insert(coll.end(),i);
}
}
int main()
{
/* initialize source collection with ""..........abcdef..........""
*/
vector<char> source(10,".");
for (int c="a"; c<="f"; c++) {
source.push_back(c);
}
source.insert(source.end(),10,".");
PRINT_ELEMENTS(source,"source: ");
// copy all letters three elements in front of the "a"
vector<char> c1(source.begin(),source.end());
copy (c1.begin()+10, c1.begin()+16, // source range
c1.begin()+7); // destination range
PRINT_ELEMENTS(c1,"c1: ");
// copy all letters three elements behind the "f"
vector<char> c2(source.begin(),source.end());
copy_backward (c2.begin()+10, c2.begin()+16, // source range
c2.begin()+19); // destination range
PRINT_ELEMENTS(c2,"c2: ");
}
/*
source: . . . . . . . . . . a b c d e f . . . . . . . . . .
c1: . . . . . . . a b c d e f d e f . . . . . . . . . .
c2: . . . . . . . . . . a b c a b c d e f . . . . . . .
*/
Copy and insert list
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <list>
#include <deque>
#include <set>
#include <algorithm>
using namespace std;
int main()
{
list<int> coll1;
// insert elements from 1 to 9 into the first collection
for (int i=1; i<=9; ++i) {
coll1.push_back(i);
}
// copy the elements of coll1 into coll2 by appending them
vector<int> coll2;
copy (coll1.begin(), coll1.end(), // source
back_inserter(coll2)); // destination
// copy the elements of coll1 into coll3 by inserting them at the front
// - reverses the order of the elements
deque<int> coll3;
copy (coll1.begin(), coll1.end(), // source
front_inserter(coll3)); // destination
// copy elements of coll1 into coll4
// - only inserter that works for associative collections
set<int> coll4;
copy (coll1.begin(), coll1.end(), // source
inserter(coll4,coll4.begin())); // destination
}
Copy istream_iterator to ostream_iterator
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <algorithm>
#include <iterator>
#include <string>
using namespace std;
int main()
{
copy (istream_iterator<string>(cin), // beginning of source
istream_iterator<string>(), // end of source
ostream_iterator<string>(cout,"\n")); // destination
}
/*
a
a
Terminate batch job (Y/N)? n
*/
Copy vector and list
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <list>
#include <deque>
#include <algorithm>
using namespace std;
int main()
{
list<int> coll1;
vector<int> coll2;
// insert elements from 1 to 9
for (int i=1; i<=9; ++i) {
coll1.push_back(i);
}
// resize destination to have enough room for the overwriting algorithm
coll2.resize (coll1.size());
/* copy elements from first into second collection
* - overwrites existing elements in destination
*/
copy (coll1.begin(), coll1.end(), // source
coll2.begin()); // destination
/* create third collection with enough room
* - initial size is passed as parameter
*/
deque<int> coll3(coll1.size());
// copy elements from first into third collection
copy (coll1.begin(), coll1.end(), // source
coll3.begin()); // destination
}
Display all elements in a vector
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <iterator>
using namespace std;
int main()
{
// create empty vector for strings
vector<string> sentence;
// reserve memory for five elements to avoid reallocation
sentence.reserve(5);
// append some elements
sentence.push_back("Hello,");
sentence.push_back("how");
sentence.push_back("are");
sentence.push_back("you");
sentence.push_back("?");
// print elements separated with spaces
copy (sentence.begin(), sentence.end(),
ostream_iterator<string>(cout," "));
cout << endl;
}
/*
Hello, how are you ?
*/
Displaying a Container"s Elements on the Standard Output with copy function
#include <algorithm>
#include <iostream>
#include <iterator>
#include <string>
#include <vector>
using namespace std;
int main( )
{
vector<int> v( 5, 9 );
copy( v.begin(), v.end(), ostream_iterator<int>( cout, " " ) );
copy( v.begin(), v.end(), ostream_iterator<int>( cout, "\n" ) );
}
Print all elements in a list with copy function
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <list>
#include <algorithm>
#include <iterator>
using namespace std;
void printLists (const list<int>& l1, const list<int>& l2)
{
cout << "list1: ";
copy (l1.begin(), l1.end(), ostream_iterator<int>(cout," "));
cout << endl << "list2: ";
copy (l2.begin(), l2.end(), ostream_iterator<int>(cout," "));
cout << endl << endl;
}
int main()
{
// create two empty lists
list<int> list1, list2;
// fill both lists with elements
for (int i=0; i<6; ++i) {
list1.push_back(i);
list2.push_front(i);
}
printLists(list1, list2);
}
/*
list1: 0 1 2 3 4 5
list2: 5 4 3 2 1 0
*/
Use copy function to print all elements in a deque
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <deque>
#include <string>
#include <algorithm>
#include <iterator>
using namespace std;
int main()
{
// create empty deque of strings
deque<string> coll;
// insert several elements
coll.assign (3, string("string"));
coll.push_back ("last string");
coll.push_front ("first string");
// print elements separated by newlines
copy (coll.begin(), coll.end(),
ostream_iterator<string>(cout,"\n"));
cout << endl;
}
/*
first string
string
string
string
last string
*/
Use copy to copy elements in one container to another container
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
using namespace std;
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << " ";
}
std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
* - fill values from first to last into the collection
* - NOTE: NO half-open range
*/
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
for (int i=first; i<=last; ++i) {
coll.insert(coll.end(),i);
}
}
int main()
{
vector<int> coll1;
list<int> coll2;
INSERT_ELEMENTS(coll1,1,9);
/* copy elements of coll1 into coll2
* - use back inserter to insert instead of overwrite
*/
copy (coll1.begin(), coll1.end(), // source range
back_inserter(coll2)); // destination range
/* print elements of coll2
* - copy elements to cout using an ostream iterator
*/
copy (coll2.begin(), coll2.end(), // source range
ostream_iterator<int>(cout," ")); // destination range
cout << endl;
}
/*
1 2 3 4 5 6 7 8 9
*/
Use copy to copy elements of one container into another container in reverse order
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
using namespace std;
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << " ";
}
std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
* - fill values from first to last into the collection
* - NOTE: NO half-open range
*/
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
for (int i=first; i<=last; ++i) {
coll.insert(coll.end(),i);
}
}
int main()
{
vector<int> coll1;
list<int> coll2;
INSERT_ELEMENTS(coll1,1,9);
/* copy elements of coll1 into coll2
* - use back inserter to insert instead of overwrite
*/
copy (coll1.begin(), coll1.end(), // source range
back_inserter(coll2)); // destination range
/* copy elements of coll1 into coll2 in reverse order
* - now overwriting
*/
copy (coll1.rbegin(), coll1.rend(), // source range
coll2.begin()); // destination range
// print elements of coll2 again
copy (coll2.begin(), coll2.end(), // source range
ostream_iterator<int>(cout," ")); // destination range
cout << endl;
}
/*
9 8 7 6 5 4 3 2 1
*/
Use copy to fill values to an array
#include <algorithm>
#include <iostream>
#include <iterator>
using namespace std;
int main( )
{
const int num_costs = 4;
const float cost[num_costs] = { 4.11, 6.77, 8.88, 9.22 };
copy( cost, cost + num_costs,ostream_iterator<float>( cout, " " ) );
const char* fruit[] = { "A", "B", "C" };
copy( fruit, fruit + sizeof( fruit ) / sizeof( fruit[0] ),
ostream_iterator<const char*>( cout, " " ) );
int year[] = { 2001, 2002, 2003, 2004, 2005 };
const int num_years = sizeof( year ) / sizeof( year[0] );
copy( year, year + num_years,ostream_iterator<int>( cout, " " ) );
sort( year, year + num_years );
copy( year, year + num_years,ostream_iterator<int>( cout, " " ) );
reverse( year, year + num_years );
copy( year, year + num_years,ostream_iterator<int>( cout, " " ) );
}
Use copy to output all elements in a container
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
using namespace std;
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << " ";
}
std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
* - fill values from first to last into the collection
* - NOTE: NO half-open range
*/
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
for (int i=first; i<=last; ++i) {
coll.insert(coll.end(),i);
}
}
int main()
{
vector<int> coll1;
list<int> coll2;
INSERT_ELEMENTS(coll1,1,9);
/* copy elements of coll1 into coll2
* - use back inserter to insert instead of overwrite
*/
copy (coll1.begin(), coll1.end(), // source range
back_inserter(coll2)); // destination range
/* print elements of coll2
* - copy elements to cout using an ostream iterator
*/
copy (coll2.begin(), coll2.end(), // source range
ostream_iterator<int>(cout," ")); // destination range
cout << endl;
}
/*
1 2 3 4 5 6 7 8 9
*/
Use std::copy to print all elements in a set
#include <iostream>
using std::cout;
using std::endl;
#include <set>
#include <algorithm>
#include <iterator> // ostream_iterator
int main()
{
double a[ 5 ] = { 2.1, 4.2, 9.5, 2.1, 3.7 };
std::set< double, std::less< double > > doubleSet( a, a + 5 );;
std::ostream_iterator< double > output( cout, " " );
cout << "doubleSet contains: ";
std::copy( doubleSet.begin(), doubleSet.end(), output );
cout << endl;
return 0;
}
/*
doubleSet contains: 2.1 3.7 4.2 9.5
*/
Use the copy algorithms: Shift the contents of vector1 left by 4 positions
#include <iostream>
#include <cassert>
#include <algorithm>
#include <vector>
#include <string>
#include <iostream>
using namespace std;
int main()
{
string s("abcdefghihklmnopqrstuvwxyz");
vector<char> vector1(s.begin(), s.end());
copy(vector1.begin() + 4, vector1.end(), vector1.begin());
vector<char>::iterator pos;
for (pos=vector1.begin(); pos!=vector1.end(); ++pos) {
cout << *pos << " ";
}
return 0;
}
/*
e f g h i h k l m n o p q r s t u v w x y z w x y z
*/
Use the generic copy to duplicate vectors
#include <iostream>
#include <cassert>
#include <algorithm>
#include <vector>
#include <string>
#include <iostream>
using namespace std;
int main()
{
string s("abcdefghihklmnopqrstuvwxyz");
vector<char> vector1(s.begin(), s.end());
vector<char> vector2(vector1.size());
// Copy vector1 to vector2:
copy(vector1.begin(), vector1.end(), vector2.begin());
assert (vector1 == vector2);
vector<char>::iterator pos;
for (pos=vector1.begin(); pos!=vector1.end(); ++pos) {
cout << *pos << " ";
}
cout << "\n\n\n\n";
for (pos=vector2.begin(); pos!=vector2.end(); ++pos) {
cout << *pos << " ";
}
return 0;
}
/*
a b c d e f g h i h k l m n o p q r s t u v w x y z
a b c d e f g h i h k l m n o p q r s t u v w x y z
*/