AP Computer Science Princples

Collaboration

Pair programming & code reviews: fewer bugs and more ideas

Incremental dev

design → code → test → refine.

Break big problems into parts.

Comments

explain purpose, not syntax. Help others

read your code.

Iterative

plan → prototype → test → feedback →

revise. Revisit steps as needed.

Testing

use known inputs/outputs. Check edge cases

(empty, boundary, extreme).

Debugging

add print statements to trace variables. Test small

sections alone.

Binary

Each bit is equal to the power of 2, with 2^0=1

Bin→dec

multiply each bit × place value, sum. 1011₂

Type Reversible? Examples

= 8+0+2+1 = 11.

Dec→bin

divide by 2, track remainders bottom→top.

Overflow

result exceeds max bits → error. 8-bit: 255+1 = overflow

Roundoff

real #s in finite bits → approx. 1/3 ≠ 0.333… in binary

Analog

sampling at intervals. Higher rate = better quality, more space

Metadata

data about data (for example: resolution, file size, date)

List

an ordered, flexible collection of items stored under a single name

Reasonable

polynomial (n, n², n³).

Unreasonable

exponential (2ⁿ).

Undecidable

no algorithm solves ALL cases (e.g. halting problem).

Lossy

some data removed permanently → smaller but can't restore. e.g. JPEG, MP3.

Lossless

original fully restored. e.g. PNG, ZIP, GIF.

Internet

network of networks.

World Wide Web

web pages on the internet

Protocols

TCP (reliable delivery), IP (addressing), HTTP/S (web), DNS (name→IP).

Packets

data split into chunks → routed independently → reassembled.

Threats

phishing, DDoS, malware, keyloggers.

Phishing

A type of cyberattack where criminals impersonate a trusted person or organization to trick you into revealing sensitive information, such as passwords, credit card numbers, or personal data.

Distributed Denial-of-Service (DDoS)

is a malicious attempt to disrupt normal traffic of a server, service, or network by overwhelming the target or its surrounding infrastructure with a flood of Internet traffic.

Malware

malicious software (malware) is used to disrupt, damage, or gain unauthorized access to a computer, network, or devices.

Keyloggers

It is a surveillance tool, either software or hardware, that secretly records every keystroke made on a computer or mobile device.

duel-use

tech has BOTH positive & negative effects.

social media

connects people but spreads mis-info & privacy.

Digital divide

unequal access based on income, location, age.

Algorithmic bias

biased data in → biased results out.

PII

Personally identifiable info (once leaked cannot be un-leaked)

Cookies

They track browsing, terms of service allow data collection