CS106L

CS106L 2023 winter official website

About

为什么要学CS106L？24年国庆节之后入职的实习需要使用到C++和C#，想要趁着国庆假期将斯坦福的CS106B以及CS106L都学习一下。

lecture1 welcome

CS106L focus on code: what makes it good, what powerful and elegant code looks like.

Only STL.

understand how and why C++ was made.

C language: no objects or classes, difficult to write generic code

C++ was created by Bjarne Stroutstrup in 1983

Design philosophy of C++:

1. only add features if they solve an actual problem
2. programmers should be free to choose their own sytle
3. compartmentalization is key
4. Allow the programmer full control of if they want it
5. don't sacrifice performance except as a last resort
6. enforce safety at compile time whenever possible

lecture2 types and structs

using namespace std; is not good style

STL - standard template library

Namespace for the STL is std

2.1 types

C++ fundamental types:

#include <string>
int val = 5; //32 bits
char ch = 'F'; //8 bits (usually)
float decimalVal1 = 5.0; //32 bits (usually)
double decimalVal2 = 5.0; //64 bits (usually)
bool bVal = true; //1 bit
std::string str = "sarah";

C++ is a statically typed language, everything with a name(variables, functions, etc) is given a type before runtime

dynamically typed: everything with a name is given a type at runtim based on the thing's current value

If the type is wrong, Python crash during runtime, but C++ compile error and the code will never run

2.2 overloading

overloading: defien two functions with the same name but different types.

int half(int x, int divisor = 2) {
  return x / divisor;
}
double half(double x) { 
  return x / 2;
}

half(4) // uses version (1), returns 2
half(3, 3) // uses version (1), returns 1
half(3.0) // uses version (2), returns 1.5

2.3 structs

Two methods of initializing a struct.

#include <iostream>
struct Student {
    std::string name;
    std::string state;
    int age;
};

void printStudentInfo(Student s) {
    std::cout << s.name << std::endl;
    std::cout << s.state << std::endl;
    std::cout << s.age << std:: endl; 
}

int main () {
    Student s1;
    s1.name = "Charles";
    s1.state = "Zhejiang";
    s1.age = 24;
    printStudentInfo(s1);

    Student s2 = {"Chi Le", "Suzhou", 22};
    printStudentInfo(s2);
}

2.4 std::pair

std::pair is an STL build-in struct with two fields of any type.

std::pair is a template, you specify the types of the fields inside <> for each pair object you make

The fields in std::pair s are named first and second

std::pair<bool, Student> lookupStudent(string name) {
    Student blank;
    if (notFound(name)) return std::make_pair(false, blank);
    Student result = getStudentWithName(name);
    return std::make_pair(true, result);
}
std::pair<bool, Student> output = lookupStudent(“Julie”);

2.5 type deduction with auto 类型自动推倒auto

the type of a variant is deduced by the compiler

Note:

auto d = "Hello"; // char* -> it is a C string