C++ Tutorial/STL Algorithms Modifying sequence operations/replace copy if
Содержание
Copy one vector to another vector, replacing elements greater than 9 with 100
<source lang="cpp">#include <iostream>
- include <algorithm>
- include <vector>
using namespace std; bool greater9( int ); int main() {
const int SIZE = 10; int a[ SIZE ] = { 10, 2, 10, 4, 16, 6, 14, 8, 12, 10 }; // Replace 10s in v1 with 100 vector< int > v1( a, a + SIZE ); replace( v1.begin(), v1.end(), 10, 100 ); // Copy v4 to c2, replacing elements greater than 9 with 100 vector< int > v4( a, a + SIZE ); vector< int > c2( SIZE ); replace_copy_if( v4.begin(), v4.end(), c2.begin(), greater9, 100 ); cout << endl; return 0;
} bool greater9( int x ) {
return x > 9;
}</source>
std::replace_copy_if with predicate
<source lang="cpp">#include <iostream> using std::cout; using std::endl;
- include <algorithm>
- include <vector>
- include <iterator>
bool greater9( int ); int main() {
int a[ 10 ] = { 10, 2, 10, 4, 16, 6, 14, 8, 12, 10 }; std::ostream_iterator< int > output( cout, " " ); std::vector< int > v4( a, a + 10 ); // copy of a std::vector< int > c2( 10 ); // instantiate vector c2 cout << "Vector v4 before replacing all values greater than 9 and copying:\n; std::copy( v4.begin(), v4.end(), output ); // copy v4 to c2, replacing elements greater than 9 with 100 std::replace_copy_if(v4.begin(), v4.end(), c2.begin(), greater9, 100 ); cout << "\nVector c2 after replacing all values greater than 9 in v4:\n "; std::copy( c2.begin(), c2.end(), output ); cout << endl; return 0;
} bool greater9( int x ) {
return x > 9;
}</source>
Vector v4 before replacing all values greater than 9 and copying: 10 2 10 4 16 6 14 8 12 10 Vector c2 after replacing all values greater than 9 in v4: 100 2 100 4 100 6 100 8 100 100
Use replace_copy_if to print all elements with a value less than 5 replaced with 42
<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; int main() {
list<int> coll; INSERT_ELEMENTS(coll,2,6); INSERT_ELEMENTS(coll,4,9); PRINT_ELEMENTS(coll); // print all elements with a value less than 5 replaced with 42 replace_copy_if(coll.begin(), coll.end(), // source ostream_iterator<int>(cout," "), // destination bind2nd(less<int>(),5), // replacement criterion 42); // new value cout << endl;
}</source>
2 3 4 5 6 4 5 6 7 8 9 42 42 42 5 6 42 5 6 7 8 9
Use replace_copy_if to print each element while each odd element is replaced with 0
<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; int main() {
list<int> coll; INSERT_ELEMENTS(coll,2,6); INSERT_ELEMENTS(coll,4,9); PRINT_ELEMENTS(coll); // print each element while each odd element is replaced with 0 replace_copy_if(coll.begin(), coll.end(), // source ostream_iterator<int>(cout," "), // destination bind2nd(modulus<int>(),2), // replacement criterion 0); // new value cout << endl;
}</source>
2 3 4 5 6 4 5 6 7 8 9 2 0 4 0 6 4 0 6 0 8 0