Boolean Algebra is used to describe “logical relations” in the same way that Algebra is used to describe “numeric relations”. Boolean algebra takes two or more conditional statements and compares their truth value against each other.
The Logical And Operator compares two Boolean expressions.
The Logical And Operator is expressed with 2 ampersand keys placed together (the ‘and’ character on the ‘7’ key).
&& // ← Logical And Operator
Let’s look at all possible expressions and their results using Boolean values.
true && true // ⇒ returns true
true && false // ⇒ returns false
false && true // ⇒ returns false
false && false // ⇒ returns false
As you can see, both of the operators Boolean values must be true for the statement to return true.
There is also a Logical Or Operator. This operator returns true if *either of the Boolean values being evaluated are true.
The Logical Or Operator is specified using two pipe characters, This character is typically found on as the “shift character” on the backslash, which is the key above “return”.
|| // ← Logical Or Operator
Following the above example, let’s look at all the possible statement combinations and the result.
true || true // ⇒ returns true
true || false // ⇒ returns true
false || true // ⇒ returns true
false || false // ⇒ returns false
As you can see, only one of the Boolean values needs to be true for the statement to return true.