(C++) operator!=

 

operator!= is the operator to determine if two instances are different.

 

The following code uses operator!= to determine that three is not equal to four:

 

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#include <iostream> int main() {   if (3 != 4) std::cout << "Three is not equal to four" << std::endl; }

 

operator!= is encapsulated by the functor std::not_equal_to.

 

 

 

 

 

Advice

 

 

• In some cases, writing != as =! will not be a syntax error, but almost certainly will be a logic error that has an effect at execution time [1]

 

 

 

 

 

References

 

1. Paul Deitel, Harvey Deitel. C++11 for programmers (2nd edition). 2014. ISBN: 978-0-13-343985-4. Chapter 2.4, Common Programming Error 2.2. page 32: 'Reversing the order of the pair of symbols in the operators !=, >= and < (by writing them as =!, => and =< respectively) is normally a syntax error. In some cases, writing != as =! will not be a syntax error, but almost certainly will be a logic error that has an effect at execution time.'