bjc-r/cur/programming/python/csed_python/open_python.html at 28482e4fd32bd8c5c9d40015d8d600c28e0630be · cs10/bjc-r · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
<!DOCTYPE html>
<html>
    <head>
        <script src="/bjc-r/llab/loader.js"></script>
        <title>Starting Up Python</title>
    <!-- Global site tag (gtag.js) - Google Analytics -->
<script async src="https://www.googletagmanager.com/gtag/js?id=UA-176402054-1"></script>
<script>
  window.dataLayer = window.dataLayer || [];
  function gtag(){dataLayer.push(arguments);}
  gtag('js', new Date());

  gtag('config', 'UA-176402054-1');
</script>
</head>
    <body>
        <p class="alert alert-danger quoteRed">
            Python can be tricky to run at first on some computers. Always ask if you're having trouble.
        </p>
        <h3>On Mac OS X: (including in-lab computers)</h3>
        <p>
            You'll be running python from the Teriminal application that we learned about on the last page.
        </p>
        <h3>On Windows</h3>
        <p>
            Python may not be set up properly on windows. If you are unable to get python to work from the command line (as explained below) here is a <a href="https://docs.python.org/3.4/faq/windows.html" target="_blank">link</a> that will help you get things set up if you'd like to work on your Windows machine.
        </p>
        <h3>Running Python</h3>
        <p>
            The first step is to open the Python <b>interpreter</b>. On the command line in your terminal, use the command <code>python3</code>. You should see something similar to the following:
        </p>
        <p><pre><code>
s273-2 [2] ~ # python3
Python 3.4.3 (default, Nov 17 2016, 01:08:31)
[GCC 4.8.4] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>
        </code></pre></p>
        <br />
        <p>
            We're now using Python! Notice that we still have a <b>prompt</b>, but it looks like this now: <code>>>></code>. The <code>>>></code> indicates that we're using Python right now, and is where we can type Python code. After typing a line of code, hitting <code>enter</code> will tell the python interpreter to run the instruction. Try typing the following into the interpreter:
        </p>
        <p><pre><code>
>>> 3 + 5
8
        </code></pre></p>
        <p class="alert alert-danger quoteRed">
            If the text cursor is on a line beginning with <code>>>></code>, the command line window has an active python interpreter open. <b>That means we can't do commands like <code>cd</code>, or <code>ls</code>, because the program is expecting Python code.</b> To leave the python interpreter, type the exit command <code>exit()</code> and press <code>enter</code>.
        <p><pre><code>
>>> exit()
Alonzos-MacBook:~ alonzo$$
        </code></pre></p>
        <p>
            Any functions or variables created in the python interpreter are erased when the <code>exit()</code> command is run.
        </p>

        <p>
          Here are some basic concepts about the Python <b>intepreter</b> you should understand before you move on:
          <ul>
            <li>Open the interpreter with the command <code>python</code> or <code>python3</code>.</li>
            <li>The interpreter will run the code you typed every time you press <code>enter</code>.</li>
            <li>
              Exit the interpreter with the command <code>exit()</code>. Now you can use commands like <code>cd</code> and <code>ls</code> again, and whatever you did in Python is lost.
            </li>
          </ul>
        </p>

    </body>
</html>