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[TOC]

## Week 0 - Scratch

- 進制/ASCII/Unicode
- Pseudocode/複雜度
- Algorithm/Artificial Intelligence
- Scratch

## Week 1 - C

- Compiler
- Source Code $\rightarrow$ Machine Code
- [Visual Code for CS50](https://cs50.dev/)

// hello.c

#include <stdio.h>

int main(void){
    printf("hello, world\n");
}

- [Manual pages for the C standard library](https://manual.cs50.io/)

// hello.c

#include <stdio.h>
#include <cs50.h>

int main(void) {
    string answer = get_string("What's your name? ");
    printf("hello, %s\n", answer);
}

// comapre.c
#include <stdio.h>
#include <cs50.h>

int main(void) {
    int x = get_int("What's x? ");
    int y = get_int("What's y? ");

    if (x < y) {
        printf("x is less than y\n");
    } else if (x > y) {
        printf("x is greater than y\n");
    } else {
        printf("x is equal to y\n");
    }
}

// agree.c
#include <stdio.h>

int main() {
    char c = get_char("Do you agree? ");

    if (c == 'y' || c == 'Y') {
        printf("Agreed.\n");
    } else if (c == 'n' || c == 'N') {
        printf("Not agreed.\n");
    }
}

// meow.c
#include <stdio.h>

int main() {
    int i = 0;
    while (i < 3) {
        printf("meow\n");
        i++;
    }
}

// meow.c
#include <stdio.h>

void meow(void) {
  printf("Meow!\n");
}

// First void means that the function does not return a value
// Second void means that the function does not accept any arguments

int main(void) {
    meow();
}

// meow.c
#include <stdio.h>

void meow(int n);

int main(void) {
    meow(3);
}

void meow(int n) {
    for (int i = 0; i < n; i++) {
        printf("meow\n");
    }
}

// calculator.c
#include <cs50.h>
#include <stdio.h>

int add(int a, int b);

int main(void) {
    int x = get_int("x: ");
    int y = get_int("y: ");

    printf("%i\n", add(x, y));
}

int add(int a, int b) {
    return a + b;
}

- Graphic User Interface (GUI)
- Commandline

// calculator.c

#include <cs50.h>
#include <stdio.h>

int main(void)
{
    int x = get_int("x: ");
    int y = get_int("y: ");

    printf("%.20f\n", (double) x / (double) y);
}

### Data Types

- integer / unsigned integer / chat / float / double / bool / string
- void

### Operators

- $+$, $-$, $*$, $/$, $\%$
- true / false
- $\&\&$, $||$, $!$
- $>$, $<$, $>=$, $<=$
- $!=$, $==$

### Conditional Statements

- if / else / else if
- switch
- case
- default
- ?:

int x;
if (expr) {
    x = 5;
} else {
    x = 6;
}

// int x = (expr) ? 5 : 6;

### Loops

- while / do-while
- for

for (start; expr; increment) {
    
}

### Command Line

- `ls`: list
- `cd`: change directory
- `pwd`: print work directory
- `cp`: copy
- `rm`: remove
- `rm -f <file>`
- `rm -r <directory>`
- `mv`: move


## Week 2 - Arrays

- make / [clang](https://zh.wikipedia.org/zh-tw/Clang)

1. preprocessing
2. compiling
3. assembling
4. linking

- Debugger / [Rubber duck debugging](https://zh.wikipedia.org/wiki/%E5%B0%8F%E9%BB%84%E9%B8%AD%E8%B0%83%E8%AF%95%E6%B3%95)


// scores.c
#include <stdio.h>
#include <cs50.h>

int main(void) {
    int scores[3];
    for (int i = 0; i < 3; i++) {
        scores[i] = get_int("Score: ");
    }

    printf("Average: %f\n", (scores[0] + scores[1] + scores[2]) / 3.0);
}

// hi.c
#include <stdio.h>
#include <cs50.h>

int main(void) {
    string s = "hi!";
    printf("%c%c%c\n", s[0], s[1], s[2]);
}

// hi.c
#include <stdio.h>
#include <cs50.h>

int main(void) {
    string words[2];
    
    words[0] = "HI!";
    words[1] = "BYE!";
    
    printf("%c%c%c\n", words[0][0], words[0][1], words[0][2]);
    printf("%c%c%c%c\n", words[1][0], words[1][1], words[1][2], words[1][3]);
}

// hi.c
#include <stdio.h>
#include <cs50.h>

int main(void) {
    string words[1];

    words[0] = "HI!";

    printf("%i %i %i %i\n", words[0][0], words[0][1], words[0][2], words[0][3]); 
    // 72 73 33 0
}

// length.c
#include <stdio.h>
#include <cs50.h>

int string_length(string s);

int main(void) {
    string name = get_string("Name: ");
    int length = string_length(name);
    printf("%i\n", length);
}

int string_length(string s) {
    int i = 0;
    while (s[i] != '\0') {
        i++;
    }

    return i;
}

// string.c
#include <cs50.h>
#include <stdio.h>
#include <string.h>

int main(void) {
    string s = get_string("Input: ");
    printf("Output: ");
    for (int i = 0; i < strlen(s); i++) {
        printf("%c", s[i]);
    }
    printf("\n");
}

// uppercase.c
#include <stdio.h>
#include <cs50.h>
#include <ctype.h>
#include <string.h>

int main(void) {
    string s = get_string("Before: ");
    printf("After: ");
    for (int i = 0, n = strlen(s); i < n; i++) {
            printf("%c", toupper(s[i]));
    }
    printf("\n");
}

// greet.c
#include <stdio.h>
#include <cs50.h>

int main(int argc, string argv[]) {
    if (argc == 2)
        printf("hello, %s\n", argv[1]);
    else
        printf("hello, world\n");
}

// status.c
#include <cs50.h>
#include <stdio.h>

int main(int argc, string argv[]) {
    if (argc != 2) {
        printf("Missing command-line argument\n");
        return 1;
    }
    printf("hello, %s\n", argv[1]);
    return 0;
}

### Functions

### Variables and Scope

### Debugging (“Step through”)

### Duplicate of 'Debugging (“Step into”)'

### Arrays

### Command Line Arguments

## Week 3 - Algorithms

## Week 4 - Memory

## Week 5 - Data Structures

## Week 6 - Python

## Artificial Intelligence

## Week 7 - SQL

## Week 8 - HTML, CSS, JavaScript

## Week 9 - Flask

## Week 10 - Cybersecurity

## Reference

[Problem Set](https://cs50.harvard.edu/x/2024/psets/0/)
[Progress](https://cs50.me/cs50x)