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partition
Prototypetemplate <class ForwardIterator, class Predicate> ForwardIterator partition(ForwardIterator first, ForwardIterator last, Predicate pred) DescriptionPartition reorders the elements in the range [first, last) based on the function object pred, such that the elements that satisfy pred precede the elements that fail to satisfy it. The postcondition is that, for some iterator middle in the range [first, last), pred(*i) is true for every iterator i in the range [first, middle) and false for every iterator i in the range [middle, last). [1] The return value of partition is middle.DefinitionDefined in the standard header algorithm, and in the nonstandard backwardcompatibility header algo.h.Requirements on types
Preconditions
ComplexityLinear. Exactly last  first applications of pred, and at most (last  first)/2 swaps.ExampleReorder a sequence so that even numbers precede odd numbers.int A[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}; const int N = sizeof(A)/sizeof(int); partition(A, A + N, compose1(bind2nd(equal_to<int>(), 0), bind2nd(modulus<int>(), 2))); copy(A, A + N, ostream_iterator<int>(cout, " ")); // The output is "10 2 8 4 6 5 7 3 9 1". [1] Notes[1] The relative order of elements in these two blocks is not necessarily the same as it was in the original sequence. A different algorithm, stable_partition, does guarantee to preserve the relative order. See alsostable_partition, Predicate, function objectCopyright © 1999 Silicon Graphics, Inc. All Rights Reserved. TrademarkInformation
