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copied!<p>let's say on the command-line you have:</p> <pre><code>C:\> C:\Documents and Settings\fred\My Documents\Downloads\google-python-exercises \google-python-exercises\hello.py John </code></pre> <p>to make it easier to read, let's just shorten this to:</p> <pre><code>C:\> hello.py John </code></pre> <p><code>argv</code> represents all the items that come along via the command-line input, but counting starts at zero (0) not one (1): in this case, "<code>hello.py</code>" is element 0, "<code>John</code>" is element 1</p> <p>in other words, <code>sys.argv[0] == 'hello.py'</code> and <code>sys.argv[1] == 'John'</code> ... but look, how many elements is this? 2, right! so even though the numbers are 0 and 1, there are 2 elements here.</p> <p><code>len(sys.argv) >= 2</code> just checks whether you entered <em>at least</em> two elements. in this case, we entered exactly 2.</p> <p>now let's translate your code into English:</p> <pre><code>define main() function: if there are at least 2 elements on the cmd-line: set 'name' to the second element located at index 1, e.g., John otherwise there is only 1 element... the program name, e.g., hello.py: set 'name' to "World" (since we did not get any useful user input) display 'Hello' followed by whatever i assigned to 'name' </code></pre> <p>so what does this mean? it means that if you enter:</p> <ul> <li>"<code>hello.py</code>", the code outputs "<code>Hello World</code>" because you didn't give a name</li> <li>"<code>hello.py John</code>", the code outputs "<code>Hello John</code>" because you did</li> <li>"<code>hello.py John Paul</code>", the code still outputs "<code>Hello John</code>" because it does not save nor use <code>sys.argv[2]</code>, which was "<code>Paul</code>" -- can you see in this case that <code>len(sys.argv) == 3</code> because there are 3 elements in the <code>sys.argv</code> list?</li> </ul>

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