Pseudocode Booleans

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• Slides

In pseudocode, we can create variables that store values using the Boolean data type. These variables can only store one of two values: true or false. So, a Boolean value is really the simplest data value we can imagine - it is a single binary bit representing a value of true or false. In some systems, we may also refer to these values as 0 or 1, but in pseudocode we’ll just use true and false.

To create a variable that stores a Boolean value in pseudocode, we can use the following assignment statements:

x <- true
y <- false

In pseudocode, both true and false are keywords in the language. They represent the special boolean values true and false, and cannot be used as the name of a variable or procedure. Since they are values and not strings, we do not have to put them in quotation marks.

Converting Between Data Types

We can use the special BOOLEAN() procedure to convert any value to a Boolean value. Here are the basic rules for that conversion:

• Strings: "true" will evaluate to true and "false" will evaluate to false. Capitalization doesn’t matter. All other values are undefined.
• Numbers: 0 will evaluate to false, and any other value will be true.

The reverse works as well - Boolean values can be provided as input to the STRING() or NUMBER() procedures, and the outputs produced there will match these rules. Specifically, the true value will convert to the number $1$, but any non-zero number would be valid.