map value_comp() in C++ STL
The std::map::value_comp() is a function in C++ STL. It returns a function object that compares objects of type std::map::value.
Syntax:
value_compare value_comp() const
Parameters: It does not accept any parameters.
Returns: This method returns a function object that compares objects of type std::map::value.
Time Complexity: O(1)
Below examples illustrate the map::value_comp() method:
Example 1:
// C++ program to illustrate // map::value_comp() method #include <iostream> #include <map> using namespace std; int main() { map< char , int > m = { { 'a' , 1 }, { 'b' , 2 }, { 'c' , 3 }, { 'd' , 4 }, { 'e' , 5 }, }; auto last = *m.rbegin(); auto i = m.begin(); cout << "Map contains " << "following elements" << endl; do { cout << i->first << " = " << i->second << endl; } while (m.value_comp()(*i++, last)); return 0; } |
Output:
Map contains following elements a = 1 b = 2 c = 3 d = 4 e = 5
Example 2:
// C++ Program to illustrate // map::rbegin() method #include <iostream> #include <map> using namespace std; int main() { map< char , char > m = { { 'a' , 'A' }, { 'b' , 'B' }, { 'c' , 'C' }, { 'd' , 'D' }, { 'e' , 'E' }, }; auto last = *m.rbegin(); auto i = m.begin(); cout << "Map contains " << "following elements" << endl; do { cout << i->first << " = " << i->second << endl; } while (m.value_comp()(*i++, last)); return 0; } |
Output:
Map contains following elements a = A b = B c = C d = D e = E
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