Charles Zhang chaojian-zhang

Put general language/usage notes here.

Snippets

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Print value of Pi to Any Number of Accuracy

VirtualBox: https://www.virtualbox.org/

Debian 11 Image:

Convert images to video: ffmpeg -framerate 4 -start_number 51 -i _DSC12%d.jpg -c:v libx264 -r 4 output.mp4 (Recommendataion) Use Screen2Gif's editor instead.
Convert video into gif
Convert video into image sequence:
Crop video: ffmpeg -i in.mp4 -vf crop=w:h:x:y out.mp4
Change video frame rate:
Scale video resolution: ffmpeg -i input.avi -vf scale=320:240 output.avi
Scaleing while keeping aspect ratio: ffmpeg -i input.jpg -vf scale=320:-1 output_320.png
Scale images: ffmpeg -i input.jpg -vf scale=320:240 output_320x240.png
Multiple filters (separate using comma): ffmpeg -i 1.mp4 -vf "crop=720:720:264:0, scale=320:-1" 1.gif
Trim/Cut video: ffmpeg -i input.mp4 -ss 00:05:20 -t 00:10:00 -c:v copy -c:a copy output1.mp4

(List is up-to-date per 20220322)

Overview

All prices negotiable; LIST PRICE MAY CHANGE (and become higher); Most of my books are either new or almost new because I always keep my books in very good conditions. Some even have insightful notes.

Most books are purchased within the past 4 years.

[Bundles]

Troubleshooting

Type or namespace could not be found even after AddReference: There are a few potential causes - 1) Dynamic assembly won't work e.g. Single Executable option in publish; 2) Be careful you are actually passing the assembly reference to AddReferences() not as the third "global" object to CSharpScript.RunAsync(); 3) During publishing, might want to "Delete existing files" because old assemblies can mess up with assembly references.
By the way the differences between "Add" and "With" is the latter replaces everything, while the former adds to the list; And "Imports" is equivalent to "using" in code.

	int main()
	{
	int a = 5;
	int* b = &a;
	int c[] = {1, 2, 3, 4, 5};
	return 0;
	}

	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="utf-8">
	<title>Enter Title Here</title>
	<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
	<meta name="description" content="Starter Template">
	<meta name="author" content="Charles Zhang">

	<link href="style.css" rel="stylesheet" />

	{
	# Put the following into user settings JSON file to change the sick annoying default bright red preformatted code text foreground color for Monokai Dimmed color theme
	"editor.tokenColorCustomizations": {
	"[Monokai Dimmed]": {
	"textMateRules": [
	{
	"scope": "markup.inline.raw",
	"settings": {
	"foreground": "#675b5b",
	}

	// dotnet add package SFML.Net --version 2.5.0
	// dotnet add package OpenTK --version 4.0.0-pre9.1

	using OpenTK.Graphics.OpenGL;
	using OpenTK.Windowing.Desktop;
	using SFML.Graphics;
	using SFML.Window;

	namespace CSharpSFMLWithOpenTK
	{

	# Self-elevate the script - put this at beginning of file
	if (!([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole] "Administrator")) { Start-Process pwsh.exe "-NoProfile -ExecutionPolicy Bypass -File `"$PSCommandPath`"" -Verb RunAs; Exit }

	# Example of a command that requires admin priviledge
	[Environment]::SetEnvironmentVariable("MY_ENV_PATH", "$PSScriptRoot", "Machine")