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for-loop on cmd-line

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  for-loop on cmd-line Gisle Vanem <gvanem@broadpark.no> - 2012-10-11 13:24 +0200
    Re: for-loop on cmd-line suzaku <satorulogic@gmail.com> - 2012-10-11 04:50 -0700
    Re: for-loop on cmd-line suzaku <satorulogic@gmail.com> - 2012-10-11 04:50 -0700

#31108 — for-loop on cmd-line

Hello list. I'm a newbie when it comes to Python.

I'm trying to turn this:

 def print_sys_path():
    i = 0
    for p in sys.path:
      print ('sys.path[%2d]: %s' % (i, p))
      i += 1

into a one-line python command (in a .bat file):

  python -c "import sys,os; i=0; for p in sys.path: print('sys.path[%%2d]: %%s' %% (i, p)); i+=1"

But:
  File "<string>", line 1
    import sys,os; i=0; for p in sys.path: print('sys.path[%2d]: %s' % (i, p)); i+=1
                          ^
SyntaxError: invalid syntax

The caret is on the 'for'. What's the problem?

--gv

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#31109

According to the document (http://docs.python.org/using/cmdline.html#interface-options),
> When called with -c command, it executes the Python statement(s) given as command. Here command may contain multiple statements separated by newlines. Leading whitespace is significant in Python statements!

So you should replace the semicolon with newline.

BTW, the loop can be simplified using `enumerate` like this:

   for i, p in enumerate(sys.path):
     

On Thursday, October 11, 2012 7:24:31 PM UTC+8, Gisle Vanem wrote:
> Hello list. I'm a newbie when it comes to Python.
> 
> 
> 
> I'm trying to turn this:
> 
> 
> 
>  def print_sys_path():
> 
>     i = 0
> 
>     for p in sys.path:
> 
>       print ('sys.path[%2d]: %s' % (i, p))
> 
>       i += 1
> 
> 
> 
> into a one-line python command (in a .bat file):
> 
> 
> 
>   python -c "import sys,os; i=0; for p in sys.path: print('sys.path[%%2d]: %%s' %% (i, p)); i+=1"
> 
> 
> 
> But:
> 
>   File "<string>", line 1
> 
>     import sys,os; i=0; for p in sys.path: print('sys.path[%2d]: %s' % (i, p)); i+=1
> 
>                           ^
> 
> SyntaxError: invalid syntax
> 
> 
> 
> The caret is on the 'for'. What's the problem?
> 
> 
> 
> --gv

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#31110

According to the document (http://docs.python.org/using/cmdline.html#interface-options),
> When called with -c command, it executes the Python statement(s) given as command. Here command may contain multiple statements separated by newlines. Leading whitespace is significant in Python statements!

So you should replace the semicolon with newline.

BTW, the loop can be simplified using `enumerate` like this:

   for i, p in enumerate(sys.path):
     

On Thursday, October 11, 2012 7:24:31 PM UTC+8, Gisle Vanem wrote:
> Hello list. I'm a newbie when it comes to Python.
> 
> 
> 
> I'm trying to turn this:
> 
> 
> 
>  def print_sys_path():
> 
>     i = 0
> 
>     for p in sys.path:
> 
>       print ('sys.path[%2d]: %s' % (i, p))
> 
>       i += 1
> 
> 
> 
> into a one-line python command (in a .bat file):
> 
> 
> 
>   python -c "import sys,os; i=0; for p in sys.path: print('sys.path[%%2d]: %%s' %% (i, p)); i+=1"
> 
> 
> 
> But:
> 
>   File "<string>", line 1
> 
>     import sys,os; i=0; for p in sys.path: print('sys.path[%2d]: %s' % (i, p)); i+=1
> 
>                           ^
> 
> SyntaxError: invalid syntax
> 
> 
> 
> The caret is on the 'for'. What's the problem?
> 
> 
> 
> --gv

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