C++ Map Library - operator!= Function

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Description

The C++ function std::map::operator!= tests whether two maps are equal or not.

Declaration

Following is the declaration for std::map::operator!= function form std::map header.

C++98

template <class Key, class T, class Compare, class Alloc>
bool operator!= ( const map<Key,T,Compare,Alloc>& m1,
                  const map<Key,T,Compare,Alloc>& m2);

Parameters

• m1 − First map object.

• m2 − Second map object.

Return value

Returns true if both map are not equal otherwise false.

Exceptions

This function doesn't throw exception.

Time complexity

Linear i.e. O(n)

Example

The following example shows the usage of std::map::operator!= function.

#include <iostream>
#include <map>

using namespace std;

int main(void) {
   map<char, int> m1;
   map<char, int> m2;

   m1.emplace('a', 1);

   if (m1 != m2)
      cout << "Both maps not are equal." << endl;

   m1 = m2;

   if (!(m1 != m2))
      cout << "Both maps are equal." << endl;

   return 0;
}

Let us compile and run the above program, this will produce the following result −

Both maps not are equal.
Both maps are equal.