Zybooks Chapter 3

Branch

A sequence of statements only executed under a certain.

if branch

A branch taken only IF an expression is true

if-else

Has two branches. The first branch is executed IF an expression is true, ELSE the other branch is executed.

If-elseif-else branches

Each branch's expression is checked in sequence; as soon as one branches expression is found to be true, that branch is taken. If no expression is found true, execution will reach the else branch, which then executes.

If statement

Executes a group of statements if an expression is true. The statements in a branch must be indented some number of spaces, typically four spaces.

Equality operator (==)

Evaluates to true if the left and right sides are equal.

Inequality operators (!=)

Evaluates to true if the left and right sides are not equal or different

Boolean

An expression involving an equality or inequality operator. It has just two values: True or False. True and False are keywords in Python and must be capitalized.

If-else statement

Executes one group of statements when an expression is true, and another group of statements when the expression is false.

Multi-branch if-else statements

Each branch's expression is checked in sequence. As soon as one branch's expression is found to be true, that branch's statement executes (and no subsequent branch is considered). If no expression is true, the else branch executes.

Relational operator

Checks how one operand's value relates to another, like being greater than.

Operator Chaining

(a < b < c) Chaining performs comparisons left to right, evaluating a < b first. If the result is true, then b < c is evaluated next. If the result of the first comparison a < b is False, then there is no need to continue evaluating the rest of the expression.

Logical operator

Treats operands as being True and False, and evaluates to True or False. Include AND, OR, and NOT

Logical AND

True when both of its operands are True

Logical OR

True when at least one of its two operands are True

Logical NOT

True when its one operand is False, and vice-versa.

Boolean AND

True when both operands are True

Boolean OR

True when at least one operand is True.

Boolean NOT(opposite)

True when the single operand is False (and False when operand is True)

Nested if-else statements

A branch's statements can include any valid statements, including another if-else statement.

Precedence rules

The order in which operators are evaluated in an expression.

Code Block

A series of statements that are grouped together. Identified by its indentation level, i.e, the number of blank columns from the left edge.