replace_if(3C++) - replace_if(3C++)
Standard C++ Library Copyright 1998, Rogue Wave Software, Inc.
NAMEreplace_if
- Substitutes elements in a collection with new values.
SYNOPSIS
#include <algorithm>
template <;class ForwardIterator,
class Predicate,
class T>
void replace_if (ForwardIterator first,
ForwardIterator last,
Predicate pred
const T& new_value);
DESCRIPTION
The replace_if algorithm replaces element referred to by iterator i in
the range [first, last) with new_value when the following condition
holds: pred(*i) == true.
COMPLEXITY
Exactly last - first applications of the predicate are done.
EXAMPLE
//
// 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, 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,
// s.b. 1 2 3 4 5 6 11 8 9 10
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,
// s.b. 13 13 13 4 5 6 11 8 9 10
cout << "List after replace_if " << endl << " ";
copy(v.begin(),v.end(),
ostream_iterator<int,char>(cout," "));
cout << endl << endl;
return 0;
}
Program OutputThe 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
WARNINGS
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.
SEE ALSO
replace, replace_copy, replace_copy_if
Rogue Wave Software 02 Apr 1998 replace_if(3C++)
