In order to build control flow into our program, we want to be able to check if something is true or not. A boolean expression is a statement that can either be True or False.
Let’s go back to the ‘waking up’ example. The first question, “Is today a weekday?” can be written as a boolean expression:
This expression can be True if today is Tuesday, or it can be False if today is Saturday. There are no other options.
Consider the phrase:
Is this a boolean expression?
No, this statement is an opinion and is not objectively True or False. Someone else might say that “Wednesday is the best weekday,” and their statement would be no less True or False than the one above since there is no objective answer to what the best day of the week is.
How about the phrase:
Is this a boolean expression?
Yes! This expression can only be True or False, which makes it a boolean expression. Even though the statement itself is false (Sunday starts with the letter ‘C’), it is still a boolean expression.
Instructions
Determine if the following statements are boolean expressions or not. If they are, set the matching variable to the right to "Yes" and if not set the variable to "No". Here’s an example of what to do:
Example statement:
This is an opinion and not a boolean expression, so you would set example_statement to "No" in the editor to the right. Okay, now it’s your turn:
Statement one:
Statement two:
Statement three:
Statement four: