Lecture 1:
Welcome to CS106L!
CS106L, Winter 2025
Today’s Agenda
• Introductions!
• The Pitch
• Course Logistics
Introductions
Now you can meet (some of) each other!
• Turn to the people next to you and introduce yourselves!
• Potential Conversation Topics:
o What's something you're into and not into?
o Why do you want to take this class?
The Pitch
Why C++?
“The invisible foundation of everything”
Valorant
[source]
CS: GO 2
[source]
…and many more!
High Frequency Trading
[source]
Self Driving
[source]
GPU Programming
[source]
Arduino
[source]
And much, much more!
• Databases (MySQL, MongoDB)
• Web Browsers (Chrome, Safari, Edge)
• Virtual Reality (Quest)
• Low level ML (PyTorch, TensorFlow, OpenAI)
• Compilers, virtual machines (JVM, LLVM, GCC)
• Operating Systems (Windows)
“The invisible foundation of everything”
C++ is great for…
• Handling lots of data
• And handling it very efficiently
• And doing it in an elegant, readable way
C++ was created in 1983, still #2!
[TIOBE Index, December 2024]
C++ in Industry
CppCon 2018
[source]
The C++ Community
• C++ has a MASSIVE user base
• C++ Standard continues to be revised every three years
We are here!
C++ C++03 C++14 C++20
C++26
1979 1983 1998 2003 2011 2014 2017 2020 2023
C++98 C++11 C++17 C++23
What is C++?
A valid C++ program
#include <iostream>
#include <string>
int main() {
auto str = std::make_unique<std::string>("Hello World!");
std::cout << *str << std::endl;
return 0;
}
// Prints "Hello World!"
Also a valid C++ program
C++ is backwards
#include "stdio.h" compatible with
C. Neat!
#include "stdlib.h"
int main(int argc, char *argv) {
printf("%s", "Hello, world!\n");
// ^a C function!
return EXIT_SUCCESS;
}
Also a valid C++ program
#include "stdio.h"
#include "stdlib.h"
int main(int argc, char *argv) {
asm(".LC0:\n\t"
".string \"Hello, world!\"\n\t"
"main:\n\t"
"push rbp\n\t"
"mov rbp, rsp\n\t"
"sub rsp, 16\n\t"
"mov DWORD PTR [rbp-4], edi\n\t"
"mov QWORD PTR [rbp-16], rsi\n\t"
"mov edi, OFFSET FLAT:.LC0\n\t"
"call puts\n\t");
return EXIT_SUCCESS;
}
C++ History: Assembly
section .text
global _start ;must be declared for linker (ld)
_start: ;tell linker entry point
mov edx,len ;message length
mov ecx,msg ;message to write
mov ebx, 1 ;file descriptor (stdout)
mov eax, 4 ;system call number (sys_write)
int 0x80 ;call kernel
mov eax, 1 ;system call number (sys_exit)
int 0x80 ;call kernel
section .data
msg db 'Hello, world!' ,0xa ;our dear string
len equ $ - msg ;length of our dear string
C++ History: Assembly
• Unbelievably simple instructions
• Extremely fast (when well-written)
• Complete control over your program
Why don’t we always use assembly?
C++ History: Assembly
• Unbelievably simple instructions
• Extremely fast (when well-written)
• Complete control over your program
• A lot of code (even for simple tasks)
• Very hard to understand
• Extremely unportable
C++ History: Invention of C
• Dennis Ritchie created C in 1972 to
much praise.
• C made it easy to write code that was:
• Fast
• Simple
• Cross platform
• Compilers! Source Code → Assembly
• Learn to love it in CS107!
Ken Thompson and Dennis Ritchie,
creators of the C language
C++ History: Invention of C
• C was popular because it was simple
• “When I read C I know what the output Assembly is going to look like”
—Linus Torvalds, creator of Linux
• However, C has some weaknesses:
• No objects or classes
• Difficult to write generic or templated code
• Tedious to write large programs
C++ History: Welcome to C++!
• In 1983, the beginnings of C++ were created by Danish computer
scientist Bjarne Stroustrup
• He wanted a language that was
• Fast
• Simple to use
• Cross-platform
• Had high level features
Bjarne Stroustrup, the man himself ☺
C++ Design Philosophy
• Express ideas and intent directly in code.
• Enforce safety at compile time whenever possible.
• Do not waste time or space.
• Compartmentalize messy constructs.
• Allow the programmer full control, responsibility, and choice.
"Code should be elegant and efficient; I hate to have
to choose between those"
—Bjarne Stroustrup
C++ Design Philosophy (Summarized)
• Readable
• Safety
• Efficiency
• Abstraction
• Multi-paradigm
A valid C++ program
#include "stdio.h"
#include "stdlib.h"
int main(int argc, char *argv) {
asm(".LC0:\n\t"
".string \"Hello, world!\"\n\t"
"main:\n\t"
"push rbp\n\t"
"mov rbp, rsp\n\t"
"sub rsp, 16\n\t"
"mov DWORD PTR [rbp-4], edi\n\t"
"mov QWORD PTR [rbp-16], rsi\n\t"
"mov edi, OFFSET FLAT:.LC0\n\t"
"call puts\n\t");
return EXIT_SUCCESS;
}
A valid C++ program
#include "stdio.h"
#include "stdlib.h"
int main(int argc, char *argv) {
printf("%s", "Hello, world!\n");
// ^a C function!
return EXIT_SUCCESS;
}
A valid C++ program
#include <iostream> Templates!
Smart
#include Pointers
<string>
int main() {
auto str = std::make_unique<std::string>("Hello World!");
std::cout << *str << std::endl;
return 0;
} Streams Operator Overloading
// Prints "Hello World!"
Topics We’ll Cover
Week 1 Welcome Types & Structs
Week 2 Initialization & References Streams
Week 3 Containers Iterators & Pointers
Week 4 Classes Template Classes
Week 5 Template Functions Functions & Lambdas
Week 6 Operator Overloading Special Member Functions
Week 7 Move Semantics std::optional and Type Safety
RAII, Smart Pointers, C++
Week 8
Projects
Why take CS106L?
CS106B vs. CS106L
• Focus on concepts like • Focus is on code: what
abstractions, makes it good, what
recursion, pointers powerful and elegant
etc. code looks like
• Bare minimum C++ in • The real deal: No
order to use these Stanford libraries,
concepts only STL
• Understand how and why
C++ was made
When might you use C++?
• In one of Stanford’s classes
• CS 111: Operating Systems Principles
• CME 213: Introduction to parallel computing using MPI, openMP, and CUDA
• CS 143: Compilers
• CS 144: Introduction to Computer Networking
• CS 248A: Computer Graphics: Rendering, Geometry, and Image Manipulation
• MUSIC 256A: Music, Computing, Design: The Art of Design
• …and more!
• And in real life!
“Nobody should call themselves a professional if they
only know one language” —Bjarne Stroustrup
C++ helps develop good coding hygiene
• Am I using objects the way they’re meant to be used?
• Type checking, type safety
• Am I using memory efficiently?
• Reference/copy semantics, move semantics
• Am I modifiying something I’m not supposed to?
• const and const correctness
• Other languages relax these restrictions
Magnus vs. Me
What questions do you have?
bjarne_about_to_raise_hand
Course Logistics
Asking Questions
• We welcome questions!
• Feel free to raise your hand at
any time with a question
• We'll also pause periodically to
solicit questions and check
understanding
Access and Accommodations
• Disabled students are a valued and essential part of the Stanford
community. We welcome you to our class!
• Please work with OAE but also let us know if there's anything we can
do to make the course more accessible to you.
• Don't be shy about asking for accommodations if problems arise.
We're very reasonable people and will do whatever we can to help.
Community Norms
• Shame-free zone
• Treat your peers and instructors with kindness and respect
• Be curious
• Communication is key!
• Recognized we are all in-process (humility, question posing, avoid
perfectionism)
Guiding Principles
• We will do everything we can to support you. We want to provide
flexibility to the best of our ability!
• We want to hear your feedback so we can ensure the class is going as
smoothly as possible for everyone
• Please communicate with us if any personal circumstances or issues
arise! We are here to support you :)
What questions do you have?
bjarne_about_to_raise_hand
Lecture
• Held Tuesdays and Thursdays from 3:00pm – 4:20pm in Turing
Auditorium
• Lecture is not recorded.
• Attendance is required. Short participations quizzes (1-2 questions)
will be given at the beginning of lecture starting in week 2. All
students are given 2 free absences.
Illness
• If you are sick, for the wellbeing of yourself and others please stay
home, take care of yourself, and reach out to us – we never want you
to feel that you must attend class if you are not feeling well!
• Similarly, if you have an emergency or exceptional circumstance,
please reach out to us so that we can help!
Office Hours
• OH times are TBD and will be in person
o These will be settled by week 2 (before the first assignment)
• We want to talk to you! Come talk!
• Extra OH weeks 9 – 10!
• Watch the course website (cs106l.stanford.edu) and Ed for more info.
Assignments
• There will be 8 short weekly assignments (typically will take 1 hour at
most depending on experience)
o Submissions will be on paperless as directed on the assignment handout!
• Assignments will be released on Fridays and due in one week (the
following Friday)
o All students have three free late days.
Grading
• Grading is S/NC. We expect everyone to get an S!
• How do you get an S?
o Attend 11 of the 13 lectures between Week 2 and Week 9
o Successful completion of 6 out of 8 weekly assignments
Get in touch with us!
• Here are the best ways to communicate with us!
• Email us: cs106l-win2425-staff@lists.stanford.edu
o Please use this email and not our individual emails so we both receive the
message!
• Public or private post on Ed
• After class or in our office hours
What questions do you have?
bjarne_about_to_raise_hand
