Logical AND and OR

Truth tables

Logical AND and OR

Before you advance any further in the lesson, here’s the truth tables for logical AND ( && ) and logical OR ( || ).

&& (AND)

A	B	A && B
`true`	`true`	`true`
`true`	`false`	`false`
`false`	`true`	`false`
`false`	`false`	`false`

|| (OR)

A	B	A \|\| B
`true`	`true`	`true`
`true`	`false`	`true`
`false`	`true`	`true`
`false`	`false`	`false`

Truth tables are used to represent the result of all the possible combinations of inputs in a logical expression. A represents the boolean value on the left-side of the expression and B represents the boolean value on the right-side of the expression.

Truth tables can be helpful for visualizing the different outcomes from a logical expression. However, do you notice anything peculiar about the truth tables for logical AND and OR?

Short-circuiting

In some scenarios, the value of `B` in logical AND and OR doesn't matter.

In both tables, there are specific scenarios where regardless of the value of B, the value of A is enough to satisfy the condition.

For example, if you look at A AND B, if A is false, then regardless of the value B, the total expression will always evaluate to false because both A and B must be true in order for the entire expression to be true.

This behavior is called short-circuiting because it describes the event when later arguments in a logical expression are not considered because the first argument already satisfies the condition.

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