map value_comp() in C++ STL

In this article we will be discussing the working, syntax and examples of map::value_comp() function in C++ STL.

What is a Map in C++ STL?

Maps are the associative container, which facilitates to store the elements formed by a combination of key value and mapped value in a specific order. In a map container the data is internally always sorted with the help of its associated keys. The values in the map container are accessed by its unique keys.

What is map::value_comp()?

map::value_comp() is an inbuilt function in C++ STL which is declared in

It is a type of function pointer or a function object which does the comparison of the two values of the same type in a particular set and returns true if the first element is smaller than the second element in the container, else it returns false.

Syntax

Map_name.value_comp(key& k);

Parameter

This function accepts no parameter.

Return value

This function returns a comparison object of the associated set container.

Example

Input

map<char, int> newmap;
newmap[‘a’] = 1;
newmap[‘b’] = 2;
newmap[‘c’] = 3;
set<int>::value_compare cmp = myset.value_comp()

Output

1
2
3

Example

 Live Demo

#include <iostream>
#include <map>
using namespace std;
int main() {
   map<char, int> TP = {
      { 'a', 10 },
      { 'b', 20 },
      { 'c', 30 },
      { 'd', 40 },
      { 'e', 50 },
   };
   auto temp = *TP.rbegin();
   auto i = TP.begin();
   cout <<"Elements in map are : \n";
   do {
      cout<< i->first << " = " << i->second<< endl;
   } while (TP.value_comp()(*i++, temp));
   return 0;
}

Output

Elements in map are :
a = 10
b = 20
c = 30
d = 40
e = 50