Predicate Version of partial_sort
Illustrates how to use the predicate version of the partial_sort Standard Template Library (STL) function in Visual C++.
template<class RandomAccessIterator, class Compare> inline
void partial_sort(
RandomAccessIterator First,
RandomAccessIterator Middle,
RandomAccessIterator Last,
Compare Compare
)
Remarks
Nota
The class/parameter names in the prototype do not match the version in the header file. Some have been modified to improve readability.
The partial_sort algorithm sorts the smallest n elements, where n = Middle - First of the sequence [First, Last). The remaining elements end up in the range [Middle..Last) in an undefined order. The predicate version of partial_sort uses the compare function for comparisons.
Example
// partial_sortPV.cpp
// compile with: /EHsc
// Illustrates how to use the predicate version
// of the partial_sort function.
//
// Functions:
// partial_sort : Sort the smallest N elements in a sequence.
// disable warning C4786: symbol greater than 255 character,
// okay to ignore
#pragma warning(disable: 4786)
#include <iostream>
#include <algorithm>
#include <functional>
#include <vector>
using namespace std ;
int main()
{
const int VECTOR_SIZE = 8 ;
// Define a template class vector of int
typedef vector<int> IntVector ;
//Define an iterator for template class vector of strings
typedef IntVector::iterator IntVectorIt ;
IntVector Numbers(VECTOR_SIZE) ;
IntVectorIt start, end, it ;
// Initialize vector Numbers
Numbers[0] = 4 ;
Numbers[1] = 10;
Numbers[2] = 70 ;
Numbers[3] = 30 ;
Numbers[4] = 10;
Numbers[5] = 69 ;
Numbers[6] = 96 ;
Numbers[7] = 7;
start = Numbers.begin() ; // location of first
// element of Numbers
end = Numbers.end() ; // one past the location
// last element of Numbers
cout << "Before calling partial_sort\n" << endl ;
// print content of Numbers
cout << "Numbers { " ;
for(it = start; it != end; it++)
cout << *it << " " ;
cout << " }\n" << endl ;
// sort the smallest 4 elements in the sequence
partial_sort(start, start+4, end, less<int>()) ;
cout << "After calling partial_sort\n" << endl ;
cout << "Numbers { " ;
for(it = start; it != end; it++)
cout << *it << " " ;
cout << " }\n" << endl ;
}
Output
Before calling partial_sort
Numbers { 4 10 70 30 10 69 96 7 }
After calling partial_sort
Numbers { 4 7 10 10 70 69 96 30 }
Requirements
Header: <algorithm>