The logical, !
, operator is a prefix operator that negates, or reverses, the Boolean value of its operand. It returns false
when the operand is true
, and returns true
, when the operand is false
.
Note that unlike the &&
and ||
operators, the !
operator acts on a single value.
Assume we have the following variables that hold Boolean values.
let a = true let b = false
Prepending the !
operator to both values will result in the opposite Boolean:
print(!a) // Prints: false print(!b) // Prints: true
The !
operator can also be used to negate the value of an expression as long as that expression is contained within parentheses. The following example first executes the logic within the parentheses and then negates it.
print(!(true && false)) // Prints: true
The resulting value will be true
since true && false
results in false
and !false
is true
.
Instructions
In NotOperator.swift, we’ve declared a variable feelingWell
and set up an if
/else
statement that determines a course of action according to how we feel.
Place the following print()
statements within their correct code blocks:
- print("Embrace the day!")
- print("Have some vitamins and take care of yourself 🤒")