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==Copy only unique elements in a vector into another vector==

<source lang="cpp">

#include <iostream>
using std::cout;
using std::endl;
#include <algorithm>
#include <vector>
#include <iterator>
int main()
{
const int SIZE = 10;
int a1[ SIZE ] = { 1, 3, 5, 7, 9, 1, 3, 5, 7, 9 };
std::vector< int > v1( a1, a1 + SIZE ); // copy of a
std::ostream_iterator< int > output( cout, " " );
cout << "Vector v1 contains: ";
std::copy( v1.begin(), v1.end(), output );
std::vector< int > results1;
std::unique_copy( v1.begin(), v1.end(), std::back_inserter( results1 ) );
cout << "\nAfter unique_copy results1 contains: ";
std::copy( results1.begin(), results1.end(), output );
return 0;
}
/*
Vector v1 contains: 1 3 5 7 9 1 3 5 7 9
After unique_copy results1 contains: 1 3 5 7 9 1 3 5 7 9
*/
</source>

==Copy standard input to standard output while compressing spaces==

<source lang="cpp">

/* 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>
using namespace std;
bool bothSpaces (char elem1, char elem2)
{
return elem1 == " " && elem2 == " ";
}
int main()
{
// don"t skip leading whitespaces by default
cin.unsetf(ios::skipws);
/* copy standard input to standard output
* - while compressing spaces
*/
unique_copy(istream_iterator<char>(cin), // beginning of source: cin
istream_iterator<char>(), // end of source: end-of-file
ostream_iterator<char>(cout), // destination: cout
bothSpaces); // duplicate criterion
}
/*
a
a
Terminate batch job (Y/N)? n
*/
</source>

==Read all characters while compressing whitespaces==

<source lang="cpp">

/* 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 <string>
#include <algorithm>
#include <iterator>
#include <locale>
using namespace std;
class bothWhiteSpaces {
private:
const locale& loc; // locale
public:
/* constructor
* - save the locale object
*/
bothWhiteSpaces (const locale& l) : loc(l) {
}
/* function call
* - returns whether both characters are whitespaces
*/
bool operator() (char elem1, char elem2) {
return isspace(elem1,loc) && isspace(elem2,loc);
}
};
int main()
{
string contents;
// don"t skip leading whitespaces
cin.unsetf (ios::skipws);
//Read all characters while compressing whitespaces
unique_copy(istream_iterator<char>(cin), // beginning of source
istream_iterator<char>(), // end of source
back_inserter(contents), // destination
bothWhiteSpaces(cin.getloc())); // criterion for removing
// process contents
// - here: write it to the standard output
cout << contents;
}
/*
string
string
asdf

string
string
asdf
Terminate batch job (Y/N)? n
*/
</source>

==Remove adjacent duplicates: unique_copy==

<source lang="cpp">

#include <string>
#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
const string hello("Hello, how are you?");
string s(hello.begin(),hello.end());
// iterate through all of the characters
string::iterator pos;
for (pos = s.begin(); pos != s.end(); ++pos) {
cout << *pos;
}
cout << endl;
/* remove adjacent duplicates
* - unique() reorders and returns new end
* - erase() shrinks accordingly
*/
s.erase (unique(s.begin(), s.end()), s.end());
cout << "no duplicates: " << s << endl;
}
/*
Hello, how are you?
no duplicates: Helo, how are you?
*/
</source>

==Use unique_copy to copy elements in an array to list with back_inserter==

<source lang="cpp">

#include <iostream>
#include <list>
#include <algorithm>
#include <string>
using namespace std;
int main( ) {
string arrStr[5] = {"A", "B", "A", "D", "E"};
list<string> lstStrDest;
unique_copy(&arrStr[0], &arrStr[5], back_inserter(lstStrDest));
for (list<string>::iterator p = lstStrDest.begin( );
p != lstStrDest.end( ); ++p) {
cout << *p << endl;
}
}
/*
A
B
A
D
E
*/
</source>

==Use unique_copy to print elements with consecutive duplicates removed==

<source lang="cpp">

/* 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>
/* 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);
}
}

using namespace std;
bool differenceOne (int elem1, int elem2)
{
return elem1 + 1 == elem2 || elem1 - 1 == elem2;
}
int main()
{
// source data
int source[] = { 1, 4, 4, 6, 1, 2, 2, 3, 1, 6, 6, 6, 5, 7,
5, 4, 4 };
int sourceNum = sizeof(source)/sizeof(source[0]);
// initialize coll with elements from source
list<int> coll;
copy(source, source+sourceNum, // source
back_inserter(coll)); // destination
PRINT_ELEMENTS(coll);
// print elements with consecutive duplicates removed
unique_copy(coll.begin(), coll.end(), // source
ostream_iterator<int>(cout," ")); // destination
cout << endl;
}
/*
1 4 4 6 1 2 2 3 1 6 6 6 5 7 5 4 4
1 4 6 1 2 3 1 6 5 7 5 4
*/
</source>

==Use unique_copy to print elements without consecutive entries that differ by one==

<source lang="cpp">

/* 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>
/* 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);
}
}

using namespace std;
bool differenceOne (int elem1, int elem2)
{
return elem1 + 1 == elem2 || elem1 - 1 == elem2;
}
int main()
{
// source data
int source[] = { 1, 4, 4, 6, 1, 2, 2, 3, 1, 6, 6, 6, 5, 7,
5, 4, 4 };
int sourceNum = sizeof(source)/sizeof(source[0]);
// initialize coll with elements from source
list<int> coll;
copy(source, source+sourceNum, // source
back_inserter(coll)); // destination
PRINT_ELEMENTS(coll);
// print elements without consecutive entries that differ by one
unique_copy(coll.begin(), coll.end(), // source
ostream_iterator<int>(cout," "), // destination
differenceOne); // duplicates criterion
cout << endl;
}
/*
1 4 4 6 1 2 2 3 1 6 6 6 5 7 5 4 4
1 4 4 6 1 3 1 6 6 6 4 4
*/
</source>

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