CS 2010 - Fall 2025.

• There are fifty-two cards in a deck, which results in 52! possible shuffles or permutations (52! ≊ 8 * 10⁶⁷)
• The random number generator permuted a machine word, which was 32 bits. There are 2³² permutations of 32 bits = 4,294,967,296.
• The seed was taken from the system clock, which was the number of milliseconds past midnight. There are 86,400,000 milliseconds in a day.
• Moreover, the player knew the current time, and thus could narrow down the seed to roughly 250,000 numbers (4 minutes or so).
• The shuffling algorithm was off by a factor of 10⁶². (I had a bang (exclamation mark) there, but then realized that it looked like another factorial, which would have been misleading.)
• After the initial round of cards, the player would know every card remaining in the deck.
• The shuffling algorithm had other issues, including an off by one error.
• Moral: Know thy code.

Canvas Quiz of the Day (need daily password)

Click for today's quiz.

Poem of the Day

**"Regular Expression (Taylor's Version)"**

*Verse 1:*
I remember when I first learned to code at seventeen
Writing patterns in my IDE, living the developer dream
You were there in my syntax, matching every single line
Backslashes and brackets, thought you'd always be mine

But debugging at midnight, when my regex wouldn't work
You'd match things that I never meant, drove me going berserk
Greedy quantifiers taking more than they should
I was young and naive, thought I understood

*Chorus:*
We are never ever ever getting back together
My regex and me, no we're not clever
I used to think we were forever
But you're too complex, I should know better
We are never ever ever getting back together

You and your lookaheads and your capture groups
Making my code break in infinite loops

*Verse 2:*
I've got a blank space in my pattern matching
And I'll write your name... `[A-Za-z]+`
Got a long list of stack overflow questions
They'll tell you I'm insane

But I've got edge cases, they're multiplying
And you crash when I need you most
`.*` is too greedy, why are you lying?
My performance is toast

*Bridge:*
This is why we can't have nice things
(When your regex breaks everything)
One little dot-star and it's ruined
(All my parsing, I'm so wounded)

*Outro:*
I should've known from the start
You'd tear my program apart
With your cryptic notation
Causing stack overflow frustration

But maybe we could try again someday
If I learn to escape properly this way...

*Spoken:* "I'd like to thank my IDE's syntax highlighting and Stack
Overflow for helping me through this breakup."

---

*P.S. - Any resemblance to actual Taylor Swift songs is purely
intentional and done with the utmost respect for the Queen of Pop and
her incredible songwriting talent.*

When you ask for a poem about regular expressions in Taylor Swift's
style, my thought process would involve several key considerations:

**Understanding the Challenge:**
- I need to bridge two very different worlds: technical programming
  concepts (regex) and Taylor Swift's distinctive lyrical style
- This requires translating abstract, technical ideas into relatable,
  emotional narratives

**Analyzing Taylor Swift's Style:**
- Her lyrics often tell stories with vivid, specific details
- She frequently uses metaphors from everyday life (relationships,
  small towns, seasons)
- Her songs have strong emotional arcs - often about heartbreak,
  growth, or empowerment
- She uses conversational, accessible language mixed with clever wordplay
- Common themes include nostalgia, betrayal, self-discovery, and resilience

**Finding the Creative Bridge:**
- I'd look for ways regex concepts could mirror relationship or life experiences
- Pattern matching → looking for signs in relationships
- Wildcards → the unpredictability of love
- Escaping characters → protecting yourself emotionally
- Failed matches → romantic disappointments

**Technical Translation:**
- Convert regex syntax into metaphorical language
- Make programming frustrations feel like emotional struggles
- Turn debugging into a narrative of persistence and eventual success

**Structural Approach:**
- Likely format it as song verses with a chorus
- Include specific regex syntax as "inside jokes" for programmers
- Build to an empowering conclusion, as many Swift songs do

The goal would be making regex feel emotionally resonant while
capturing Swift's voice authentically.

Lecture 33: Strings and Languages.

Administrivia

Announcements

Tuesday, November 18, 2025
4:00 PM - 5:00 PM
Sloane Physics Laboratory (SPL 59)

Concept-based Generic Programming

Abstract: This talk presents programming techniques to illustrate the facilities and principles of C++ generic programming using concepts. Concepts are C++’s way to express constraints on generic code. As an initial example, it provides a simple type system that eliminate narrowing conversions and provides range checking without unnecessary notational or run-time overheads.

Concepts are used throughout to provide user-defined extensions to the type system. The aim is to show their utility and the fundamental ideas behind them, rather than to provide a detailed or complete explanation of C++’s language support for generic programming or the extensive support provided by the standard library.

The final sections briefly present design rationales and origins for key parts of the concept design, including uniform treatment of types, use patterns, the relationship to Object-Oriented Programming, value arguments, notation, concept type-matching, definition checking and static reflection (a C++26 improvements in the support of general programming).

Bio: Bjarne Stroustrup is the designer and original implementer of C++ as well as the author of The C++ Programming Language (4th Edition), A Tour of C++ (3rd edition), Programming: Principles and Practice using C++ (3rd Edition), and many popular and academic publications. Dr. Stroustrup is a professor at Columbia University in New York City. He is a member of the US National Academy of Engineering, and an IEEE, ACM, and CHM fellow. He received the 2018 Charles Stark Draper Prize, the IEEE Computer Society's 2018 Computer Pioneer Award, and the 2017 IET Faraday Medal. His research interests include distributed systems, design, programming techniques, software development tools, and programming languages. He is actively involved in the ISO standardization of C++. He holds a masters in Mathematics from Aarhus University, where he is an honorary professor, and a PhD in Computer Science from Cambridge University, where he is an honorary fellow of Churchill College.

Website: www.Stroustrup.com

Lecture: Strings and Languages.

Getting to know UNIX