Algorithm
Substitutes elements in a collection with new values, and moves the revised sequence into result.
None
#include <algorithm>
template <class InputIterator,
class OutputIterator,
class T>
OutputIterator replace_copy (InputIterator first,
InputIterator last,
OutputIterator result,
const T& old_value,
const T& new_value);
The replace_copy algorithm leaves the original sequence intact and places the revised sequence into result. For the range [first, last), the algorithm compares elements referred to by iterator i with old_value. If *i does not equal old_value, then replace_copy copies *i to result+(first-i). If *i==old_value, then replace_copy copies new_value to result+(first-i). replace_copy returns result+(last-first).
Exactly last - first comparisons between values are done.
//
// replace.cpp
//
#include <algorithm>
#include <vector>
#include <iterator>
#include <iostream>
using namespace std;
template<class Arg>
struct all_true: public unary_function<Arg, bool>
{
bool operator() (const Arg&) {return 1;}
};
int main ()
{
//
// Initialize a vector with an array of integers.
//
int arr[10] = {1,2,3,4,5,6,7,8,9,10};
vector<int> v(arr+0, arr+10);
//
// Print out original vector.
//
cout << "The original list: "<< endl << " ";
copy(v.begin(), v.end(),
ostream_iterator<int,char>(cout," "));
cout << endl << endl;
//
// Replace the number 7 with 11.
//
replace(v.begin(), v.end(), 7, 11);
//
// Print out vector with 7 replaced.
//
cout << "List after replace:" << endl << " ";
copy(v.begin(), v.end(),
ostream_iterator<int,char>(cout," "));
cout << endl << endl;
//
// Replace 1 2 3 with 13 13 13.
//
replace_if(v.begin(), v.begin()+3, all_true<int>(), 13);
//
// Print out the remaining vector.
//
cout << "List after replace_if:" << endl << " ";
copy(v.begin(), v.end(),
ostream_iterator<int,char>(cout," "));
cout << endl << endl;
//
// Replace those 13s with 17s on output.
//
cout << "List using replace_copy to cout:" << endl
<< " ";
replace_copy(v.begin(), v.end(),
ostream_iterator<int,char>(cout, " "),
13, 17);
cout << endl << endl;
//
// A simple example of replace_copy_if.
//
cout << "List w/ all elements output as 19s:" << endl
<< " ";
replace_copy_if(v.begin(), v.end(),
ostream_iterator<int,char>(cout, " "),
all_true<int>(), 19);
cout << endl;
return 0;
}
Program Output
The original list:
1 2 3 4 5 6 7 8 9 10
List after replace:
1 2 3 4 5 6 11 8 9 10
List after replace_if:
13 13 13 4 5 6 11 8 9 10
List using replace_copy to cout:
17 17 17 4 5 6 11 8 9 10
List with all elements output as 19s:
19 19 19 19 19 19 19 19 19 19
If your compiler does not support default template parameters, then you always need to supply the Allocator template argument. For instance, you need to write:
vector<int, allocator<int> >
instead of:
vector<int>
If your compiler does not support namespaces, then you do not need the using declaration for std.
replace, replace_if, replace_copy_if