Implement the equal_range() in C++

[Garrick]

Hello, I am the student of the Bsc-IT. I had learned the C++ language in first year of Bsc-IT. I can know about the functions in C++ language. I have to submit the assignment on the equal_range() function. So, I would like to know about the equal_range() function. I would also like to know how can I Implement the equal_range() function in C++ language. If there is anyone who can have the solution on the equal_range() functions then reply me!!!

[kelfro]

Hi, The equal_range() function can be the member of the <algorithm> header file. The following can be the syntax of the equal_range() function in the C++ language :

template <class ForwrdItrtr, class S>
  pair<ForwrdItrtr,ForwrdItrtr>
    equal_range ( ForwrdItrtr first, ForwrdItrtr last, const S& value );

[Zecho]

The following code of lines can demonstrates you about how can you implement the equal_range() function in the C++ language :

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
bool mgretr (int k,int l) 
{ 
return (k>l); 
}
int main ()
 {
  int mint[] = {10,20,30,30,20,10,10,20};
  vector<int> s(mint,mint+8);    
  pair<vector<int>::iterator,vector<int>::iterator> bounds;
  sort (s.begin(), s.end());                    
  bounds=equal_range (s.begin(), s.end(), 20); 
  sort (s.begin(), s.end(), mgretr);   
  bounds=equal_range (s.begin(), s.end(), 20, mgretr); 
  cout << "bounds at positions " << int(bounds.first - s.begin());
  cout << " and " << int(bounds.second - s.begin()) << endl;
  return 0;
}

Output :

bounds at positions 2 and 5

[absolute55]

PROGRAM :

int main()
{
  int B[] = { 1, 2, 3, 3, 3, 5, 8 };
  const int M = sizeof(B) / sizeof(int);
  for (int j = 2; j <= 4; ++j) 
{
    pair<int*, int*> rslt = equal_range(B, B + M, j);
    cout << endl;
    cout << "Searching for " << j << endl;
    cout << "  First position where " << j << " could be inserted: "
         << rslt.first - B << endl;
    cout << "  Last position where " << j << " could be inserted: "
         << rslt.second - B << endl;
    if (rslt.first < B + M)
      cout << "  *rslt.first = " << *rslt.first << endl;
    if (rslt.second < B + M)
      cout << "  *rslt.second = " << *rslt.second << endl;
  }
}

The output output of above can be as follows :

Searching for 2
  First position where 2 could be inserted: 1
  Last position where 2 could be inserted: 2
  *rslt.first = 2
  *rslt.second = 3
Searching for 3
  First position where 3 could be inserted: 2
  Last position where 3 could be inserted: 5
  *rslt.first = 3
  *rslt.second = 5
Searching for 4
  First position where 4 could be inserted: 5
  Last position where 4 could be inserted: 5
  *rslt.first = 5
  *rslt.second = 5

[Reegan]

The equal_range() function can returns the bounds of the largest sub-range that can includes all of the elements of the fst element and lst element with the values that can be equivalent to the val. The comparison can be test or performed using either the comp for the second version or operator< for the first version. For example :- A value, p can be considered as similar to another, (!comp(p,q) && !comp(q,p)) or q, when (!(p<q) && !(q<p)).

[opaper]

Without interfering with the numbering of the values, the largest sub-range in a specified range of values into which a given value can be inserted by the Algorithm. The equal_range() function algorithm can performs a binary search on a numbered/ordered range to demonstrate where the value of the element can be inserted without interfering with the numbering of the ranges. The library of the C++ language can includes the two versions of the algorithm.