C++ std::partition_point with multiset
Implementable on C++11/14/17
Description:
partition_point( ) is a Standard Template Library function under the <algorithm> header
which returns a iterator pointing the position where the partition is present in an already partitioned container.
which returns a iterator pointing the position where the partition is present in an already partitioned container.
partition_point( ) Definition:template <class ForwardIterator, class UnaryPredicate>
ForwardIterator partition_point (ForwardIterator first, ForwardIterator last, UnaryPredicate pred);
Return type: returns an iterator indicating the point of partition.
Working: The function partition_point() takes in 3 parameters, start position and end position iterators of the container and a predicate function which returns a boolean value (true or false).The function traverses the container from first
position to last, up till the point where the first value for which the predicate return value is false is encountered
Once encountered, iterator pointing to that location is returned.
Container used here:- std::multiset. Multisets are associative containers that can have multiple elements with same values.
Implementation:
#include <iostream>
#include <set>
#include <algorithm>
using namespace std;
//Predicate function to check whether the character element is an uppercase letter or not
bool isUpperCase(char ch)
{
if(isupper(ch))
return true;
return false;
}
//Driver
int main(int argc, char const *argv[])
{
multiset<char> arr{'A', 'B', 'C', 'D', 'e', 'f', 'g', 'h'}; //The first container, already partitioned
multiset<char> :: iterator it = partition_point(arr.begin(), arr.end(), isUpperCase); //Finding the partition point
//printing the two partitions
cout<<"UpperCase letters:"<<endl;
for(auto beg = arr.begin() ; beg != it ; beg++)
cout<<*beg<<" ";
cout<<endl;
cout<<"LowerCase letters:"<<endl;
for(auto beg = it ; beg != arr.end() ; beg++)
cout<<*beg<<" ";
cout<<endl;
return 0;
}
Sample Output:gs_katti@gsk-47534B:~/Desktop/CppSecret/algorithm_header$ ./a.outUpperCase letters:
A B C D
LowerCase letters:
e f g h
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