C++ Tutorial/STL Algorithms Modifying sequence operations/fill — различия между версиями
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Текущая версия на 13:31, 25 мая 2010
Содержание
- 1 Use fill function to overwrite all elements with "again"
- 2 Use fill function to replace the second and up to the last element but one with "hmmm"
- 3 Use std::fill to fill vector with chars
- 4 Use the generic fill algorithms: Fill first 5 positions of vector1 with X"s
- 5 Using fill to set initial values in a vector
Use fill function to overwrite all elements with "again"
<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() {
// print ten times 7.7 fill_n(ostream_iterator<float>(cout, " "), // beginning of destination 10, // count 7.7); // new value cout << endl; list<string> coll; // insert "hello" nine times fill_n(back_inserter(coll), // beginning of destination 9, // count "hello"); // new value // overwrite all elements with "again" fill(coll.begin(), coll.end(), // destination "again"); // new value PRINT_ELEMENTS(coll,"coll: ");
}</source>
7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.7 coll: again again again again again again again again again
Use fill function to replace the second and up to the last element but one with "hmmm"
<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() {
// print ten times 7.7 fill_n(ostream_iterator<float>(cout, " "), // beginning of destination 10, // count 7.7); // new value cout << endl; list<string> coll; // insert "hello" nine times fill_n(back_inserter(coll), // beginning of destination 9, // count "hello"); // new value // replace the second and up to the last element but one with "hmmm" list<string>::iterator pos1, pos2; pos1 = coll.begin(); pos2 = coll.end(); fill (++pos1, --pos2, // destination "hmmm"); // new value PRINT_ELEMENTS(coll,"coll: ");
}</source>
7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.7 coll: hello hmmm hmmm hmmm hmmm hmmm hmmm hmmm hello
Use std::fill to fill vector with chars
<source lang="cpp">#include <iostream> using std::cout; using std::endl;
- include <algorithm> // algorithm definitions
- include <vector> // vector class-template definition
- include <iterator> // ostream_iterator
int main() {
std::vector< char > chars( 10 ); std::ostream_iterator< char > output( cout, " " ); std::fill( chars.begin(), chars.end(), "5" ); // fill chars with 5s cout << "Vector chars after filling with 5s:\n"; std::copy( chars.begin(), chars.end(), output ); cout << endl; return 0;
}</source>
Vector chars after filling with 5s: 5 5 5 5 5 5 5 5 5 5
Use the generic fill algorithms: Fill first 5 positions of vector1 with X"s
<source lang="cpp">#include <iostream>
- include <cassert>
- include <algorithm>
- include <vector>
- include <string>
using namespace std; int main() {
string s("Hello there"); vector<char> vector1(s.begin(), s.end()); // Fill first 5 positions of vector1 with X"s: fill(vector1.begin(), vector1.begin() + 5, "X"); vector<char>::iterator pos; for (pos=vector1.begin(); pos!=vector1.end(); ++pos) { cout << *pos << " "; } return 0;
}</source>
X X X X X t h e r e
Using fill to set initial values in a vector
<source lang="cpp">#include <algorithm>
- include <vector>
- include <iostream>
int main () {
using namespace std; vector <int> v (3); // fill all elements in the container with value 9 fill (v.begin (), v.end (), 9); cout << "Contents of the vector are: " << endl; for (size_t nIndex = 0; nIndex < v.size (); ++ nIndex) { cout << "Element [" << nIndex << "] = "; cout << v [nIndex] << endl; } return 0;
}</source>