Statements and Operators: Logical Not Operator

What is it?

The logical NOT operator in C++ is a unary operator used to reverse the logical state of its operand. If a condition is true, the logical NOT operator will make it false and vice versa. It is also known as a logical complement operator.


Syntax

The syntax of using the logical NOT operator is:

!condition

Where,

  • condition: It is a boolean expression or a logical statement that can be either true or false.



How to use it

To use the logical NOT operator, follow the below steps:

  1. Evaluate or compute a condition that can be either true or false.
  2. Apply the logical NOT operator ! to the condition.



Program code snippet example

#include <iostream>

using namespace std;

int main() {

    // Defining a condition.
    bool isRaining = false;

    // Using logical NOT operator on the condition.
    if (!isRaining) {
        cout << "It is not raining." << endl;
    } else {
        cout << "It is raining." << endl;
    }

    return 0;
}

Output:

It is not raining.



Important to know

  • The logical NOT operator reverses the state of the operand. If the condition is true, it will return false and if the condition is false, it will return true.
  • This operator is particularly useful when you want to execute a certain part of code when the condition is false.
  • It's a unary operator which means it requires only one operand.



Best practices

When using the logical NOT operator, it is important to keep the following best practices in mind:

  1. Clarity over cleverness: Do not overuse the logical NOT operator to create complex conditions. It can make your code difficult to understand. If possible, it's better to make your conditions positive rather than negative.

  2. Be careful with non-boolean expressions: In C++, any non-zero value is considered as true and zero is considered as false. When you use the logical NOT operator on a non-boolean expression, it will return true if the expression is zero and false if it's non-zero.

  3. Use parentheses to avoid confusion: When you have a complex condition with multiple operators, use parentheses to clearly specify the order of operations. This will make your code more readable and less prone to errors.



Add a logical not expression to a, b, and c to evaluate to false.