How does logical negation work

Change language. The following code shows examples of the! The following operation involving booleans :! Boolean Truthy Falsy. Logical nullish assignment??

Object initializer Operator precedence Optional chaining?. The operator short-circuits ; the second operand will not be evaluated if the first is true. Returns true 1 when its operand is false; otherwise, returns false 0. For lists and hashes, the logical negation operator returns true 1 if the list or hash is empty; otherwise it returns false 0. This means that IDL does not evaluate the second operand unless it is necessary in order to determine the proper overall answer. Short-circuiting behavior can be powerful, since it allows you to base the decision to compute the value of the second operand on the value of the first operand.

For instance, in the expression:. IDL does not evaluate Op2 if Op1 is false, because it already knows that the result of the entire operation will be false. Similarly in the expression:. IDL does not evaluate Op2 if Op1 is true, because it already knows that the result of the entire operation will be true.

Results of relational expressions can be combined into more complex expressions using the logical operators. Happens all the time to me. I'll write something, but actually meant the exact opposite. I don't think this works in all cases. I don't think there's any guarantee about the value when a null pointer value is transformed to an int. There's very little in the Standards I'm familiar with other than that a pointer can be cast to an integral type, and a constant integral expression with value zero will be cast to a null pointer value.

Null pointers are always converted to integer value zero even if the null pointer is not represented like that. Pascal Cuoq Pascal Cuoq Consider this ternary operator example: some condition?

Hope this helps. Jonathan: Correct, -1 is considered to be true Your answer states 'the strcmp function, which returns 0 for the strings being the same, and 1 for two strings not the same'. This is incorrect; it returns a non-zero value for two strings that are not the same, not 'unconditionally 1 if the strings are different'.

If you want to overload an operator, the proper prototype is: bool operator! Overloading operators works well with templates. Just make sure your operator! Good use case for overloading an operator. If you didn't have a good reason like that, however, the operator isn't usually as intuitive as a well-named function. There's always exceptions, though. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name.