此博文记录了如何在网页中简单提取视频源地址的方法，起因是STS 课程中有一个Assessment是要观看影片去回答问题。Youtube没有资源，网页操作不方便，我想把他放到VLC中播放。 软件环境 Chrome浏览器 VLC打开网络链接（视频源地址 M3U8） Windows 10 操作步骤 使用Chrome浏览器在视频播放页面按F12进入开发模式(如上图所示)。 在控制台找到Network 在搜索框输入M3U8 复制Request URL中的值在VLC中打开即可 Reference： How do we download a blob url video [closed] https://stackoverflow.com/questions/42901942/how-do-we-download-a-blob-url-video 如何下载 blob 地址的视频资源 https://www.cnblogs.com/mq0036/p/14953209.html

Create an new windwos forms project. Design Size. Add panel. design panel color,size,style. Add button. calculartor button and oper button. Coding button function. Declaring variables double fstNum,secNum; string oper; Identify button function btnCE private void btnCE_Click(object sender, EventArgs e) { textDisplay.Text = "0"; string f, s; f = Convert.ToString(fstNum); s = Convert.ToString(secNum); f = ""; s = ""; } backspace private void backspace_Click(object sender, EventArgs e) { if (textDisplay.Text.Length > 0) { textDisplay.Text = textDisplay.Text.Remove(textDisplay.Text.Length - 1, 1); } if (textDisplay.Text == "") { textDisplay.Text = "0"; } } btn9 private void btn9_Click(object sender, EventArgs e) { if (textDisplay.Text == "0") { textDisplay.Text = "9"; } else { textDisplay.Text = textDisplay.Text + "9"; } } btnAdd private void btnAdd_Click(object sender, EventArgs e) { fstNum = double.Parse(textDisplay.Text); oper = "+"; textDisplay.Text = ""; } btnPM private void btnPM_Click(object sender, EventArgs e) { double q = Convert.ToDouble(textDisplay.Text); textDisplay.Text = Convert.ToString(-1 * q); } btnC private void btnC_Click(object sender, EventArgs e) { textDisplay.Text = "0"; } benDec private void benDec_Click(object sender, EventArgs e) { if (benDec.Text == ".") { if (!textDisplay.Text.Contains(".")) { textDisplay.Text = textDisplay.Text + benDec.Text; } } } use switch statement out put equal private void btnEuq_Click(object sender, EventArgs e) { secNum = double.Parse(textDisplay.Text); switch (oper) { case "+": textDisplay.Text = (fstNum + secNum).ToString(); break; case "-": textDisplay.Text = (fstNum - secNum).ToString(); break; case "*": textDisplay.Text = (fstNum * secNum).ToString(); break; case "/": textDisplay.Text = (fstNum / secNum).ToString(); break; default: break; } } Code download：caluclator.zip Reference：

Example explainedLine 1: using System means that we can use classes from the System namespace. Line 2: A blank line. C# ignores white space. However, multiple lines makes the code more readable. Line 3: namespace is used to organize your code, and it is a container for classes and other namespaces. Line 4: The curly braces {} marks the beginning and the end of a block of code. Line 5: class is a container for data and methods, which brings functionality to your program. Every line of code that runs in C# must be inside a class. In our example, we named the class Program. Don't worry if you don't understand how using System, namespace and class works. Just think of it as something that (almost) always appears in your program, and that you will learn more about them in a later chapter. Line 7: Another thing that always appear in a C# program, is the Main method. Any code inside its curly brackets {} will be executed. You don't have to understand the keywords before and after Main. You will get to know them bit by bit while reading this tutorial. Line 9: Console is a class of the System namespace, which has a WriteLine() method that is used to output/print text. In our example it will output "Hello World!". If you omit the using System line, you would have to write System.Console.WriteLine() to print/output text. Note: Every C# statement ends with a semicolon ;. Note: C# is case-sensitive: "MyClass" and "myclass" has different meaning. Note: Unlike Java, the…