C++ Map Library - insert() Function


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Description

The C++ function std::map::insert() extends container by inserting new element in map. This function increases container size by one.

Declaration

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

C++98

pair<iterator,bool> insert (const value_type& val);

C++11

pair<iterator,bool> insert (const value_type& val);

Parameters

val − value to be inserted.

Return value

Returns a pair consisting of bool to indicate whether insertion is happened or not and returns an iterator to the newly inserted element.

Exceptions

This member function doesn't throw exception.

Time complexity

Logarithmic i.e. O(log n)

Example

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

#include <iostream>
#include <map>

using namespace std;

int main(void) {
   map<char, int> m = {
            {'a', 1},
            {'b', 2},
            {'c', 3},
            };

   m.insert(pair<char, int>('d', 4));
   m.insert(pair<char, int>('e', 5));

   cout << "Map contains following elements" << 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
a = 1
b = 2
c = 3
d = 4
e = 5
map.htm
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