Map in c++ - Standard Template Library (STL)

Map in c++ are the containers that stores elements in the form of keys and values in a mapped format.

You can use map for solving various problems,like if you want to calculate any element's frequency.

Syntax for map in c++:

map<type,type> name_of_map;

For ex:

map<int,int>m1;

where,key type is integer

           value type is integer

           name of map is 'm1'

Header file

Header file of map in c++ is  #include<map>.

Program for counting frequency of elements:

#include<iostream>

#include<map>

using namespace std;

int main()

{

int a[]={1,2,4,19,10,23,1,1,2,4,23,4,4,19};

map<int,int>m1;

for(int i=0;i<14;i++)

{

m1[a[i]]++;                         //counting elements

}

cout<<"Frequency of  1 is :"<<m1[1]<<endl;

cout<<"Frequency of  2 is :"<<m1[2]<<endl;

cout<<"Frequency of  4 is :"<<m1[4]<<endl;

cout<<"Frequency of  19 is :"<<m1[19]<<endl;

cout<<"Frequency of  10 is :"<<m1[10]<<endl;

cout<<"Frequency of  23 is :"<<m1[23]<<endl;

}