Saturday 30 January 2021

Python- Step 2: Write and run code

 How to Write and run code

Although Solution Explorer is where you manage project files, the editor window is typically where you work with the contents of files, like source code. The editor is contextually aware of the type of file you're editing, including the programming language (based on the file extension), and offers features appropriate to that language such as syntax coloring and auto-completion using IntelliSense.

  1. After creating a new "Python Application" project, a default empty file named PythonApplication1.py is open in the Visual Studio editor.

  2. In the editor, start typing print("Hello, Visual Studio") and notice how Visual Studio IntelliSense displays auto-completion options along the way. The outlined option in the drop-down list is the default completion that's used when you press the Tab key. Completions are most helpful when longer statements or identifiers are involved.

    IntelliSense auto-completion popup

  3. IntelliSense shows different information depending on the statement you're using, the function you're calling, and so forth. With the print function, typing ( after print to indicate a function call displays full usage information for that function. The IntelliSense pop up also shows the current argument in boldface (value as shown here):

    IntelliSense auto-completion popup for a function

  4. Complete the statement so it matches the following:

    Python
    print("Hello, Visual Studio")
    
  5. Notice the syntax coloration that differentiates the statement print from the argument "Hello Visual Studio". Also, temporarily delete the last " on the string and notice how Visual Studio shows a red underline for code that contains syntax errors. Then replace the " to correct the code.

    IntelliSense syntax coloring and error highlighting

     Tip

    Because one's development environment is a very personal matter, Visual Studio gives you complete control over Visual Studio's appearance and behavior. Select the Tools > Options menu command and explore the settings under the Environment and Text Editor tabs. By default you see only a limited number of options; to see every option for every programming language, select Show all settings at the bottom of the dialog box.

  6. Run the code you've written to this point by pressing Ctrl+F5 or selecting Debug > Start without Debugging menu item. Visual Studio warns you if you still have errors in your code.

  7. When you run the program, a console window appears displaying the results, just as if you'd run a Python interpreter with PythonApplication1.py from the command line. Press a key to close the window and return to the Visual Studio editor.

    Output for the first run of the program

  8. In addition to completions for statements and functions, IntelliSense provide completions for Python import and from statements. These completions help you easily discover what modules are available in your environment and the members of those modules. In the editor, delete the print line and start typing import. A list of modules appears when you type the space:

    IntellSense showing available modules for an import statement

  9. Complete the line by typing or selecting sys.

  10. On the next line, type from to again see a list of modules:

    IntellSense showing available modules for a from statement

  11. Select or type math, then continue typing with a space and import, which displays the module members:

    IntellSense showing module members

  12. Finish by importing the sincos, and radians members, noticing the auto-completions available for each. When you're done, your code should appear as follows:

    Python
    import sys
    from math import cos, radians
    

     Tip

    Completions work with substrings as you type, matching parts of words, letters at the beginning of words, and even skipped characters. See Edit code - Completions for details.

  13. Add a little more code to print the cosine values for 360 degrees:

    Python
    for i in range(360):
        print(cos(radians(i)))
    
  14. Run the program again with Ctrl+F5 or Debug > Start without Debugging. Close the output window when you're done.

No comments:

Post a Comment