std::not_equal_to in C++ with Examples
The std::not_equal_to is a functional object class for non-equality comparison and binary function object class. It returns a boolean value depending upon the condition whether the two arguments are not equal or not.
Header File:
#include <functional.h>
Template Class:
template struct not_equal_to : binary_function { // Declaration of the // not equal to operation bool operator() (const T& x, const T& y) const { return x!=y; } // Type of first parameter typedef T first_argument_type; // Type of second parameter typedef T second_argument_type; // The result is returned // as bool type typedef bool result_type; }
Syntax:
std::not_equal_to <int> ()
Parameter: This function accepts the type of the arguments T, as the parameter, to be compared by the functional call.
Return Type: It return a boolean value depending upon condition(let a & b are 2 element):
- True: If a is not equals to b.
- False: If a is equals to b.
Below is the illustration of std::not_equal_to in C++:
Program 1:
CPP
// C++ code to illustrate std::not_equal_to #include <algorithm> #include <functional> #include <iostream> #include <vector> using namespace std; // Driver Code int main() { // Initialise vectors vector< int > v1 = { 50, 55, 60, 65, 70 }; vector< int > v2 = { 50, 55, 85, 65, 70 }; // Declaring pointer of pairs pair<vector< int >::iterator, vector< int >::iterator> pairs1; // Use mismatch() function to // search first match between // v1 and v2 pairs1 = mismatch(v1.begin(), v1.end(), v2.begin(), not_equal_to< int >()); // Print the match pair cout << "The 1st match element" << " of 1st container : " ; cout << *pairs1.first << endl; cout << "The 1st match element " << "of 2nd container : " ; cout << *pairs1.second << endl; return 0; } |
Output:
The 1st match element of 1st container : 50 The 1st match element of 2nd container : 50
Program 2:
CPP
// C++ program to illustrate // std::not_equals_to #include <algorithm> #include <functional> #include <iostream> using namespace std; // Template template < typename A, typename B, typename U = not_equal_to< int > > // Function to check if a != b or not bool f(A a, B b, U u = U()) { return u(a, b); } // Driver Code int main() { int X = 1, Y = 2; // If X is not equals to Y or not cout << boolalpha; cout << f(X, Y) << '\n' ; X = -1, Y = -1; // If X is not equals to Y or not cout << f(X, Y) << '\n' ; return 0; } |
Output:
true false
Reference: http://www.cplusplus.com/reference/functional/not_equal_to/
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