AP CSP Study Guide: Data Handling & Abstraction

Variable

An abstraction inside a program that provides a named memory location to store a value.

Data Types

Types of data that can be held by variables, such as numbers, Booleans, strings, or lists.

Good Variable Names

Descriptive names for variables that enhance code readability, such as score or userName.

Assignment Operator

An operator that allows a program to change the value represented by a variable, denoted by an arrow in pseudocode.

Pseudocode Assignment Syntax

The syntax for assignment in pseudocode is variable ← expression.

Key Rule of Assignment

Assignment in programming is not algebraic; x ← x + 1 means to update x with its current value plus 1.

Swapping Values

A process that uses a temporary variable to swap the values of two variables without loss of data.

Temporary Variable

A variable used to hold a value temporarily during the process of swapping or manipulating data.

MOD Operator

An operator that returns the remainder of division between two numbers.

MOD Example: 10 MOD 3

Evaluates to 1 because 3 goes into 10 three times with a remainder of 1.

Real-World Application of MOD

Used to check if a number is even by evaluating num MOD 2.

Concatenation

The process of joining two or more strings together to form a new string.

String

An ordered sequence of characters enclosed in quotation marks.

List

An ordered collection of elements that can be numbers, strings, or other lists.

Indexing

Accessing items in a list using their position, which in AP CSP starts at 1.

LENGTH Function

Returns the total count of items in a list.

Accessing a List Element

Syntax: list[i] retrieves the value at index i.

Inserting in a List

Shifts items to the right and places a new value at the specified index.

Appending to a List

Adds a value to the very end of a list.

Removing from a List

Deletes an item at a specified index and shifts subsequent items left.

Common Mistake: Assignment Direction

Wrongly assigning with 10 ← score; should be variable ← value.

Zero-Indexing Confusion

Assuming the first item in a list is at index 0, which is incorrect in AP CSP.

Index Out of Bounds

Attempting to access an index outside the limits of a list, which results in an error.

String vs Number Addition

Strings concatenate in operations, e.g., `