COMSC20 Ch. 4 - Conditionals

Block

A group of consecutive indented statements (same indentation.) that follow boolean (ex: after if statement)

Body

The block of statements in a compound statement that follows the header.

Boolean Expression

An expression that evaluates to either True or False. EX: print(3<5) → True

Boolean Function

A function that returns a boolean value. The only possible values of the bool type are False and True.

Boolean Value

There are exactly two boolean values:True and False. Boolean values result when a boolean expression is evaluated by the Python interpreter. They have type bool.

Branch

One of the possible paths of the flow of execution determined by conditional execution.

Chained Conditional

A conditional branch with more than two possible flows of execution. In Python chained conditionals are written with if ... elif ... else statements.

Comparison Operator

One of the operators that compares two values:==, !=, >,

Condition

The boolean expression after the if statement→ in a conditional statement that determines which branch is executed.

Conditional Statement / Selection statement

A statement that controls the flow of execution depending on some condition. In Python the keywords if, elif, and else are used

Logical Operator

One of the operators that combines boolean expressions: and, or, and not.

Modulus Operator

An operator, denoted with a percent sign (%), that works on integers and yields the remainder when one number is divided by another.

Nesting

One program structure within another, such as a conditional statement inside a branch of another conditional statement.

unary selection

Form of the if statement where the else clause is omitted entirely EX:

number = int(input("Enter a non-negative number: "))

if number < 0:
    print("Sorry, negative numbers are not allowed.")
    
print("Your number was", number)

the last print is always executed → could use else: pass if uncomfortable w/ no else statement

short-circuiting

When the evaluation of a logical expression stops bc the overall value is already known → EX: print(x >= 2 and y != 0 and (x/y) > 2) → if x >= 2 is false, neither y != 0 or (x/y)>2 is evaluated

guard

A comparison put in place to cause short circuit behavior and avoid a runtime error.guard