(разн.) ← Предыдущая | Текущая версия (разн.) | Следующая → (разн.)
Replace value equal to 70 with 42 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 <set>
#include <deque>
#include <algorithm>
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;
}
int main()
{
set<int,greater<int> > coll1;
deque<int> coll2;
// insert elements from 1 to 9
for (int i=1; i<=9; ++i) {
coll1.insert(i);
}
PRINT_ELEMENTS(coll1,"initialized: ");
// transform all elements into coll2 by multiplying 10
transform (coll1.begin(),coll1.end(), // source
back_inserter(coll2), // destination
bind2nd(multiplies<int>(),10)); // operation
PRINT_ELEMENTS(coll2,"transformed: ");
// replace value equal to 70 with 42
replace_if (coll2.begin(),coll2.end(), // range
bind2nd(equal_to<int>(),70), // replace criterion
42); // new value
PRINT_ELEMENTS(coll2,"replaced: ");
}initialized: 9 8 7 6 5 4 3 2 1
transformed: 90 80 70 60 50 40 30 20 10
replaced: 90 80 42 60 50 40 30 20 10
Replace values greater than 9 in a vector with 100 with replace_if()
#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 );
// Replace values greater than 9 in v3 with 100
vector< int > v3( a, a + SIZE );
replace_if( v3.begin(), v3.end(), greater9, 100 );
return 0;
}
bool greater9( int x )
{
return x > 9;
}std::replace_if with predicate
#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 > v3( a, a + 10 ); // copy of a
cout << "Vector v3 before replacing values greater than 9:\n ";
std::copy( v3.begin(), v3.end(), output );
// replace values greater than 9 in v3 with 100
std::replace_if( v3.begin(), v3.end(), greater9, 100 );
cout << "\nVector v3 after replacing all values greater"
<< "\nthan 9 with 100s:\n ";
std::copy( v3.begin(), v3.end(), output );
cout << endl;
return 0;
}
bool greater9( int x )
{
return x > 9;
}Vector v3 before replacing values greater than 9:
10 2 10 4 16 6 14 8 12 10
Vector v3 after replacing all values greater
than 9 with 100s:
100 2 100 4 100 6 100 8 100 100
Using "std::replace_if" to replace even values by -1
#include <iostream>
#include <algorithm>
#include <vector>
// The unary predicate used by replace_if to replace even numbers
bool IsEven (const int & nNum){
return ((nNum % 2) == 0);
}
int main (){
using namespace std;
// Initialize a sample vector with 6 elements
vector <int> v (6);
// fill first 3 elements with value 8
fill (v.begin (), v.begin () + 3, 8);
// fill last 3 elements with value 5
fill_n (v.begin () + 3, 3, 5);
for (size_t nIndex = 0; nIndex < v.size (); ++ nIndex){
cout << "Element [" << nIndex << "] = ";
cout << v [nIndex] << endl;
}
cout << "Using "std::replace_if" to replace even values by -1" << endl;
replace_if (v.begin (), v.end (), IsEven, -1);
for (size_t nIndex = 0; nIndex < v.size (); ++ nIndex) {
cout << "Element [" << nIndex << "] = ";
cout << v [nIndex] << endl;
}
return 0;
}
