Flag control variable

[luke.geelen at gmail.com]

Op dinsdag 11 februari 2014 20:01:05 UTC+1 schreef luke.... at gmail.com:
> Op dinsdag 11 februari 2014 19:51:40 UTC+1 schreef Peter Otten:
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> > luke.geelen at gmail.com wrote:
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> > > well i'm trying something else but no luck :
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> > > #!bin/bash/python
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> > Hm.
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> > > import sys
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> > > import os
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> > For debugging purposes put the line
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> > print sys.argv
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> > here to see what arguments are passed to the script. When you type
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> > $ python script.py 2 * 2
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> > in the shell the "*" sign is replaced with all items in the current 
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> > directory. To avoid that you have to escape, i. e. prepend a backslash:
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> > $ python script.py 2 \* 2
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> > To illustrate:
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> > $ touch one two three
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> > $ ls
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> > one  three  two
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> > $ python -c 'import sys; print sys.argv' 2 + 2
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> > 
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> > ['-c', '2', '+', '2']
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> > $ python -c 'import sys; print sys.argv' 2 * 2
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> > ['-c', '2', 'one', 'three', 'two', '2']
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> > $ python -c 'import sys; print sys.argv' 2 \* 2
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> > 
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> > ['-c', '2', '*', '2']
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> > > a = int(sys.argv[1])
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> > > sign = (sys.argv[2])
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> > > b = int(sys.argv[3])
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> > > 
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> > > if sign == '+':
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> > >   sum = a + b
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> > >   print a, sign, b, "=", a + b
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> > >   command1 = "sudo mpg321 
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> > >   'http://translate.google.com/translate_tts?tl=en&q=%s_plus%s_equals%s'"
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> > >   % (a, b, sum) os.system (command1)
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> > > elif sign == "*":
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> > >   sum = a * b
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> > >   print a, sign, b, "=", a * b
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> > >   command1 = "sudo mpg321 
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> > >   'http://translate.google.com/translate_tts?tl=en&q=%s_times%s_equals%s'"
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> > >   % (a, b, sum)
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> > > 
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> > > when using * i get
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> > > Traceback (most recent call last):
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> > >   File "./math+.py", line 6, in <module>
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> > >     b = int(sys.argv[3])
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> > > ValueError: invalid literal for int() with base 10:
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> > > 'Adafruit-Raspberry-Pi-Python-Code'
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> > > 
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> > > i don't understand why b is a problem, it works fine with +
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> 
> 
> when using python script.py 2 \* 2
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> i get 
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> 
> Traceback (most recent call last):
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>   File "math2.py", line 5, in <module>
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>     sign = int(sys.argv[2])
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> ValueError: invalid literal for int() with base 10: '*'

i found it int(sys.argv[2]) should be sys.argv[2]

is there a way i can do python ./script.py 3 * 3 instead of python ./script 3 \* 3 ?