1. Compound Conditionals
Ball State University - CS4MS - Fall 2018

2. What is a boolean?
A variable that has 2 possible values (True or False)
A boolean is a name for something that can only be True or False
To fully understand what conditional statements are, you first need to know what a boolean is.

3. What is a conditional statement?
Tells a program to do different actions depending on whether a boolean condition is true or false.
These are usually “if” statements.
Manipulate the control flow of a program.
The control flow is the order that instructions run in a program.

4. Symbols used in conditionals...
== means “equal to”
|| means “or”
&& means “and”
Anything inside ( ) is grouped
! means “not”
!= means “not equal to”
> means “greater than”
< means “less than”

5. Truth Table for AND The symbols && stands for the AND operator.
Condition 1
AND
True
False
TRUE
FALSE
Condition 2

6. Truth Table for OR The symbols || stands for the OR operator.
Condition 1 OR
True
False
TRUE
FALSE
Condition 2

7. Truth Table for NOT The symbol ! stands for the NOT operator. NOT
Condition 1
True
False
FALSE
TRUE
The NOT operator switches a condition or boolean statement to its OPPOSITE.

8. Steps to solve conditional statements:
Pay attention to the order of operations.
Simplify expressions inside parentheses first.
Then apply operations outside parentheses.
NOTE: String variables are formatted inside quotation marks, and need to match exactly for an == expression to evaluate to true.
NOTE: Var stands for variable (which acts as a “placeholder” for a known or unknown entity).

9. Example 1
Two variables, month and day, have been initialized with the values shown below:
var month = “January”;
var day = 26;
Does the following conditional statement evaluate to True or False?
(month == “January”) && (day == 25)

10. Example 1 (Solution - Step 1)
Two variables, month and day, have been initialized with the values shown below:
var month = “January”;
var day = 26;
Does the following conditional statement evaluate to True or False?
(month == “January”) && (day == 25)
Begin by looking at the expression within the first parentheses:
(month == “January”)
The == symbol means “equal to”, and since the variable month was initialized to “January”, this expression is TRUE.

11. Example 1 (Solution - Step 2)
Two variables, month and day, have been initialized with the values shown below:
var month = “January”;
var day = 26;
Does the following conditional statement evaluate to True or False?
(month == “January”) && (day == 25)
Now, we are left with the following:
TRUE && (day == 25)
Next, simplify the expression in the remaining parentheses. Since the variable day was initialized to 26 (and NOT 25), this statement is FALSE.

12. Example 1 (Solution - Step 3)
Two variables, month and day, have been initialized with the values shown below:
var month = “January”;
var day = 26;
Does the following conditional statement evaluate to True or False?
(month == “January”) && (day == 25)
Now, we are left with the following statement:
TRUE && FALSE
The && symbol means “and”. For an “and” expression to be true, BOTH statements need to be true. Therefore, the above statement is FALSE!
Our final answer is FALSE.

13. Example 2
Two variables, count and name, have been initialized with the values shown below:
var name = “Jacob”;
var count = 7;
Does the following conditional statement evaluate to True or False?
((count > 7) || ((count + 3) < 15))

14. Example 2 (Solution - Step 1)
Two variables, count and name, have been initialized with the values shown below:
var name = “Jacob”;
var count = 7;
Does the following conditional statement evaluate to True or False?
((count > 7) || ((count + 3) < 15))
Begin by looking at the expression within the first parentheses inside the outer parentheses:
(count > 7)
The > symbol means “greater than”, and since the variable count was initialized to 7, this expression is FALSE because 7 is not greater than 7. They are equal.

15. Example 2 (Solution - Step 2)
Two variables, count and name, have been initialized with the values shown below:
var name = “Jacob”;
var count = 7;
Does the following conditional statement evaluate to True or False?
((count > 7) || ((count + 3) < 15))
Now, we are left with the following:
((FALSE) || ((count + 3) < 15))
Next, simplify the expression in the second inner set of parentheses:
((count + 3) < 15))
Since the variable count was initialized to 7, equals 10 which is indeed less than 15, so this statement is TRUE.

16. Example 2 (Solution - Step 3)
Two variables, count and name, have been initialized with the values shown below:
var name = “Jacob”;
var count = 7;
Does the following conditional statement evaluate to True or False?
((count > 7) || ((count + 3) < 15))
Now, we are left with the following:
FALSE || TRUE
Using the truth table for OR, we can simplify this expression to TRUE.
Our final answer is TRUE.