[pythonvis] Re: print"Hello world."
- From: "Jonathan C. Cohn" <jon.c.cohn@xxxxxxxxx>
- To: pythonvis@xxxxxxxxxxxxx
- Date: Tue, 29 Apr 2014 10:10:30 -0400
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
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