Chapter 3: Decision Structures and Boolean Logic

Vocabulary flashcards covering Python decision structures, relational operators, string comparison, nested conditions, logical operators, Boolean variables, walrus operators, and Turtle Graphics state functions.

Control Structure

A logical design that controls the order in which a set of statements execute.

Sequence Structure

A set of statements that execute in the exact order in which they appear.

Decision Structure

A control structure in which specific action(s) are performed only if a condition exists; also known as a selection structure.

Single Alternative Decision Structure

A decision structure that provides only one alternative path of execution; if the condition is not true, the structure is exited.

Boolean Expression

An expression tested by an if statement to determine whether it evaluates to True or False.

Relational Operator

An operator that determines whether a specific relationship exists between two values, such as greater than ($>$) or equal to ($==$).

Dual Alternative Decision Structure

A decision structure with two possible paths of execution: one path is executed if the condition is true, and the other if it is false.

String Comparison in Python

The comparison of strings character by character based on their ASCII values using relational operators.

Nested Decision Structure

A decision structure contained inside another decision structure, used to test multiple conditions sequentially.

if-elif-else Statement

A special Python decision structure that simplifies nested decision structures by supporting multiple elif clauses.

Logical Operators

Operators (and, or, not) used to connect Boolean expressions to create compound Boolean expressions.

and Operator

A binary logical operator that creates a compound Boolean expression that is true only when both subexpressions are true.

or Operator

A binary logical operator that creates a compound Boolean expression that is true when either of the subexpressions is true.

not Operator

A unary logical operator that reverses the truth value of its Boolean operand.

Short-Circuit Evaluation

The process of determining the value of a compound Boolean expression after evaluating only the first subexpression.

Boolean Variable

A variable that references one of two values, True or False, represented in Python by the bool data type.

Flag

A Boolean variable that signals whether a specific condition exists within a program.

Walrus Operator

An enhanced assignment operator ($:=$) in Python used to create assignment expressions.

Assignment Expression

An expression created with the walrus operator ($:=$) that assigns a value to a variable and returns that value.

turtle.xcor() and turtle.ycor()

Turtle Graphics functions that return the turtle's current X and Y coordinates.

turtle.heading()

A Turtle Graphics function that returns the turtle's heading, by default in degrees.

turtle.isdown()

A Turtle Graphics function that returns True if the pen is down, or False otherwise.

turtle.isvisible()

A Turtle Graphics function that returns True if the turtle is visible, or False otherwise.

turtle.pencolor()

A Turtle Graphics function that returns the pen's current color as a string when called without an argument.

turtle.fillcolor()

A Turtle Graphics function that returns the current fill color as a string when called without an argument.

turtle.bgcolor()

A Turtle Graphics function that returns the current background color as a string when called without an argument.

turtle.pensize()

A Turtle Graphics function that returns the pen's current size as a string when called without an argument.

turtle.speed()

A Turtle Graphics function that returns the current animation speed when called without an argument.