C++ Map Library - crend() Function


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Description

The C++ function std::map::erase() removes mapped value associated with key k.

Declaration

Following is the declaration for std::map::erase() function form std::map header.

C++98

size_type erase (const key_type& k);

C++11

size_type erase (const key_type& k);

Parameters

k − Key of the element to be removed.

Return value

Returns number of elements removed.

Exceptions

Throws same exception which is thrown by the Compare object.

Time complexity

Logarithmic i.e. log(n)

Example

The following example shows the usage of std::map::erase() function.

Live Demo
#include <iostream>
#include <map>

using namespace std;

int main(void) {
   /* Initializer_list constructor */
   map<char, int> m = {
            {'a', 1},
            {'b', 2},
            {'c', 3},
            {'d', 4},
            {'e', 5},
            };

   cout << "Map contains following elements before erase operation" << endl;

   for (auto it = m.begin(); it != m.end(); ++it)
      cout << it->first << " = " << it->second << endl;

   m.erase('a');

   cout << "Map contains following elements after erase operation" << endl;

   for (auto it = m.begin(); it != m.end(); ++it)
      cout << it->first << " = " << it->second << endl;

   return 0;
}

Let us compile and run the above program, this will produce the following result −

Map contains following elements before erase operation
a = 1
b = 2
c = 3
d = 4
e = 5
Map contains following elements after erase operation
b = 2
c = 3
d = 4
e = 5

map.htm

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