[pythonvis] Re: print"Hello world."
- From: Alex Hall <mehgcap@xxxxxxxxxx>
- To: pythonvis@xxxxxxxxxxxxx
- Date: Tue, 29 Apr 2014 10:13:54 -0400
On Macs, at least on mine, you don't need that line. Of course it is an option,
but if you don't include it, your script will still run. Again, this is only my
system - perhaps if I had multiple versions or a different OS things would not
work, but as it stands, they do fine with no version set. As I said, I'm not
deminishing the importance and convenience of the command, but if you are new
to Python and didn't understand about the line, you may be able to ignore it
for the moment.
On Apr 29, 2014, at 10:10 AM, Jonathan C. Cohn <jon.c.cohn@xxxxxxxxx> wrote:
> In Linux and Macintosh you want to have a #! statement on the first line
> indicating the interpreter to be loaded.
> You also need to make sure the script has the permission to execute.
>
> chmod +x ./myscript.py
>
> Then in terminal or a Xterm window you can do ./myScript.py
> I believe I sent an article this morning describing the #! line found on UNIX
> systems.
>
> Best wishes,
>
> Jonathan
>
>
>
> On Apr 29, 2014, at 8:21 AM, Hrvoje Katić <hrvojekatic@xxxxxxxxx> wrote:
>
>> Hello,
>> I just want to add that if there's a traceback or error in your code, you
>> will not be able to see it if you run .py script just by pressing Enter on
>> it since command line window will close instantly.
>> So what I do is I open a folder with .py script, and I make sure that all
>> files are unselected. Next, I press shift+applications key and then I choose
>> Open command window here option. After that, I type in hello.py and press
>> Enter. Then I can review the error details with my review cursor. That's how
>> it functions on Windows. I have to check out how it works on Linux when I
>> will be logged in at my Linux system, and I don't know for the Mac.
>> Anyway, I will be glad if I can help You all with learning Python. I already
>> wrote some programs with it such as SkypeTalking and PrintList as well as
>> Extended Winamp appmodule for NVDA. I started to learn Python since 2009,
>> and it's my favorite language, although it's not fast like C++ or JAVA, but
>> definitely easier to learn and debug code. My Python experience is
>> definitely not the best, but it grows up from time to time.
>>
>> Regards,
>> Hrvoje
>>
>> Dana 29.4.2014. 0:23, James Scholes je napisao:
>>> To answer your questions about Python and how it interacts with
>>> Terminal: Python is what we call an interpreted language, which means
>>> that instead of compiling your entire program into machine code, i.e. an
>>> executable, the Python interpreter runs your program one instruction at
>>> a time. So, if you tell it to run a file called hello.py, and that file
>>> contains these lines:
>>>
>>> print "Hello world!"
>>> print "Goodbye!"
>>>
>>> The Python interpreter will run those lines, one after the other until
>>> it reaches the end of the file. So you will, of course, see:
>>>
>>> Hello world!
>>> Goodbye world!
>>>
>>> If there are any errors while doing this, the interpreter will pick up
>>> on them and give you some useful information, called a traceback, to
>>> tell you what your program was trying to do when it failed and what
>>> exactly went wrong. So if we make a typo on the second line and try to
>>> run a program containing:
>>>
>>> pritn "Goodbye world!"
>>>
>>> You will see:
>>>
>>> Hello world!
>>> File "hello.py", line 2
>>> pritn "Goodbye world!"
>>> ^
>>> SyntaxError: invalid syntax
>>>
>>> First, our correctly typed statement is run, so we see our "Hello
>>> world!" message. But then, because we typed the N and the T in the word
>>> "print" the wrong way round, Python tells us we've made a syntax error.
>>> It also gives us the line number, the line of code being interpreted
>>> for convenience, and if you can see or be bothered counting the spaces,
>>> a visual representation of exactly where the syntax error was found on
>>> the line of code. We're also told that the offending code is contained
>>> in hello.py, which is invaluable information when you are writing
>>> programs with many different code files.
>>>
>>> The Python interpreter, on most systems, is invoked simply by typing
>>> "python" at the command line (or Terminal). This is a program, just
>>> like any other, so on Windows it must be installed. On Mac OS X and
>>> most flavours of Linux, a version of the interpreter is preinstalled
>>> which will be sufficient for your learning. When following the
>>> exercises in Learn Python the Hard Way, most of the time you will run
>>> Python with one argument; the name of the file you want to run. For
>>> example, "python hello.py". If you invoke the interpreter with no
>>> arguments, i.e. by simply typing "python", you will get an interactive
>>> prompt which allows you to run lines of Python code instantaniously.
>>> For example:
>>>
>>> Python 2.7.6 (default, Nov 10 2013, 19:24:18) [MSC v.1500 32 bit
>>> (Intel)] on win32
>>> Type "help", "copyright", "credits" or "license" for more information.
>>>>>> print "Hello world!"
>>> Hello world!
>>>>>> 10 + 10
>>> 20
>>>>>> 14 / 7
>>> 2
>>>>>> exit()
>>> Hope that helps.
>>
>>
>
> Best wishes,
>
> Jonathan
>
>
>
--
Have a great day,
Alex Hall
mehgcap@xxxxxxxxxx
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