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# stable_partition

Visual Studio .NET 2003

Classifies elements in a range into two disjoint sets, with those elements satisfying a unary predicate preceding those that fail to satisfy it, preserving the relative order of equivalent elements.

```template<class BidirectionalIterator, class Predicate>
BidirectionalIterator stable_partition(
BidirectionalIterator _First,
BidirectionalIterator _Last,
Predicate _Pred
);
```

#### Parameters

_First
A bidirectional iterator addressing the position of the first element in the range to be partitioned.
_Last
A bidirectional iterator addressing the position one past the final element in the range to be partitioned.
_Pred
User-defined predicate function object that defines the condition to be satisfied if an element is to be classified. A predicate takes single argument and returns true or false.

#### Return Value

A bidirectional iterator addressing the position of the first element in the range to not satisfy the predicate condition.

#### Remarks

The range referenced must be valid; all pointers must be dereferenceable and within the sequence the last position is reachable from the first by incrementation.

Elements a and b are equivalent, but not necessarily equal, if both Pr (a, b) is false and Pr (b, a) if false, where Pr is the parameter-specified predicate. The stable_ partition algorithm is stable and guarantees that the relative ordering of equivalent elements will be preserved. The algorithm partition does not necessarily preserve this original ordering.

#### Example

```// alg_stable_partition.cpp
// compile with: /EHsc
#include <vector>
#include <algorithm>
#include <iostream>

bool greater5 ( int value )
{
return value >5;
}

int main( )
{
using namespace std;
vector <int> v1, v2;
vector <int>::iterator Iter1, Iter2, result;

int i;
for ( i = 0 ; i <= 10 ; i++ )
{
v1.push_back( i );
}

int ii;
for ( ii = 0 ; ii <= 4 ; ii++ )
{
v1.push_back( 5 );
}

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

cout << "Vector v1 is ( " ;
for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
cout << *Iter1 << " ";
cout << ")." << endl;

// Partition the range with predicate greater10
result = stable_partition (v1.begin( ), v1.end( ), greater5 );
cout << "The partitioned set of elements in v1 is:\n ( " ;
for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
cout << *Iter1 << " ";
cout << ")." << endl;

cout << "The first element in v1 to fail to satisfy the"
<< "\n predicate greater5 is: " << *result << "." << endl;
}
```

#### Output

```Vector v1 is ( 5 1 9 2 0 5 7 3 4 5 8 5 5 5 10 6 ).
The partitioned set of elements in v1 is:
( 9 7 8 10 6 5 1 2 0 5 3 4 5 5 5 5 ).
The first element in v1 to fail to satisfy the
predicate greater5 is: 5.
```