replace_copy_if

Article
04/22/2008

Examines each element in a source range and replaces it if it satisfies a specified predicate while copying the result into a new destination range.

template<class InputIterator, class OutputIterator, class Predicate, class Type>
   OutputIterator replace_copy_if(
      InputIterator _First, 
      InputIterator _Last, 
      OutputIterator _Result, 
      Predicate _Pred, 
      const Type& _Val
   );

Parameters

_First
An input iterator pointing to the position of the first element in the range from which elements are being replaced.
_Last
An input iterator pointing to the position one past the final element in the range from which elements are being replaced.
_Result
An output iterator pointing to the position of the first element in the destination range to which elements are being copied.
_Pred
The unary predicate that must be satisfied is the value of an element is to be replaced.
_Val
The new value being assigned to the elements whose old value satisfies the predicate.

Return Value

An output iterator pointing to the position one past the final element in the destination range to where the altered sequence of elements is being copied.

Remarks

The source and destination ranges referenced must not overlap and must both be valid: all pointers must be dereferenceable and within the sequences the last position is reachable from the first by incrementation.

The order of the elements not replaced remains stable.

The operator== used to determine the equality between elements must impose an equivalence relation between its operands.

The complexity is linear; there are (_Last – _First) comparisons for equality and at most (_Last – _First) assignments of new values.

replace_copy_if has two related forms:

For information on how these functions behave, see Checked Iterators.

Example

// alg_replace_copy_if.cpp
// compile with: /EHsc
#include <vector>
#include <list>
#include <algorithm>
#include <iostream>

bool greater6 ( int value ) {
   return value >6;
}

int main( ) {
   using namespace std;
   vector <int> v1;
   list <int> L1 (13);
   vector <int>::iterator Iter1;
   list <int>::iterator L_Iter1;

   int i;
   for ( i = 0 ; i <= 9 ; i++ )
      v1.push_back( i );

   int ii;
   for ( ii = 0 ; ii <= 3 ; ii++ )
      v1.push_back( 7 );

   random_shuffle ( v1.begin( ), v1.end( ) );

   int iii;
   for ( iii = 0 ; iii <= 13 ; iii++ )
      v1.push_back( 1 );

   cout << "The original vector v1 is:\n ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")." << endl;

   // Replace elements with a value of 7 in the 1st half of a vector
   // with a value of 70 and copy it into the 2nd half of the vector
   replace_copy_if ( v1.begin( ), v1.begin( ) + 14,v1.end( ) -14,
      greater6 , 70);

   cout << "The vector v1 with values of 70 replacing those greater"
        << "\n than 6 in the 1st half & copied into the 2nd half is:\n ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")." << endl;

   // Replace elements in a vector with a value of 70
   // with a value of 1 and copy into a list
   replace_copy_if ( v1.begin( ), v1.begin( ) + 13,L1.begin( ),
      greater6 , -1 );

   cout << "A list copy of vector v1 with the value -1\n replacing "
        << "those greater than 6 is:\n ( " ;
   for ( L_Iter1 = L1.begin( ) ; L_Iter1 != L1.end( ) ; L_Iter1++ )
      cout << *L_Iter1 << " ";
   cout << ")." << endl;
}

Sample Output

The original vector v1 is:
 ( 7 1 9 2 0 7 7 3 4 6 8 5 7 7 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ).
The vector v1 with values of 70 replacing those greater
 than 6 in the 1st half & copied into the 2nd half is:
 ( 7 1 9 2 0 7 7 3 4 6 8 5 7 7 70 1 70 2 0 70 70 3 4 6 70 5 70 70 ).
A list copy of vector v1 with the value -1
 replacing those greater than 6 is:
 ( -1 1 -1 2 0 -1 -1 3 4 6 -1 5 -1 ).

Requirements

Header: <algorithm>

Namespace: std

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