C++ set - crend() Function

The C++ set::crend function returns the constant reverse iterator (const_reverse_iterator) pointing to the element preceding the first element (reversed past-the-last element) of the set.

Note: A const_reverse_iterator is an iterator that points to constant value and iterates in backward direction. Increasing a const_reverse_iterator results into moving to the beginning of the set container and decreasing it results into moving to the end of the set container. Along with this, it cannot be used to modify the contents it points to, even if the set element is not itself constant.

Note: Set is an ordered data container which implies all its elements are ordered all the time.

Syntax

• C++11

const_reverse_iterator crend() const noexcept;

Parameters

No parameter is required.

Return Value

A const_reverse_iterator to the reversed past-the-last element of the sequence container.

Time Complexity

Constant i.e, Θ(1).

Example:

In the example below, the set::crend function returns the const_reverse_iterator pointing to the element preceding the first element of the set MySet.

#include <iostream>
#include <set>
using namespace std;
 
int main (){
  set<string> MySet{"Alpha","Coding","Skills"};
  set<string>::const_reverse_iterator crit;

  crit = MySet.crend();
  crit--;
  cout<<*crit<<" ";
  crit--;
  cout<<*crit<<" ";
  crit--;
  cout<<*crit<<" ";
  return 0;
}

The output of the above code will be:

Alpha Coding Skills

Example:

Lets see another example where the set called MySet contains integer values and set::crend function is used with set::crbegin function to specify a range including all elements of the set container. Please note that, Set is an ordered data container.

#include <iostream>
#include <set>
using namespace std;
 
int main (){
  set<int> MySet{55, 25, 128, 5, 72};
  set<int>::const_reverse_iterator crit;

  for(crit = MySet.crbegin(); crit != MySet.crend(); ++crit)
    cout<<*crit<<" ";

  return 0;
}

The output of the above code will be:

128 72 55 25 5