How do I run Python script using arguments in windows command line

Question

This is my python hello.py script:

def hello(a,b):
    print "hello and that's your sum:"
    sum=a+b
    print sum
    import sys

if __name__ == "__main__":
    hello(sys.argv[2])

The problem is that it can't be run from the windows command line prompt, I used this command:

C:\Python27>hello 1 1

But it didn't work unfortunately, may somebody please help?

Answer 1

• import sys out of hello function.
• arguments should be converted to int.
• String literal that contain ' should be escaped or should be surrouned by ".
• Did you invoke the program with python hello.py <some-number> <some-number> in command line?

---

import sys

def hello(a,b):
    print "hello and that's your sum:", a + b

if __name__ == "__main__":
    a = int(sys.argv[1])
    b = int(sys.argv[2])
    hello(a, b)

Answer 2

To execute your program from the command line, you have to call the python interpreter, like this :

C:\Python27>python hello.py 1 1

If you code resides in another directory, you will have to set the python binary path in your PATH environment variable, to be able to run it, too. You can find detailed instructions here.

Answer 3

Here are all of the previous answers summarized:

• modules should be imported outside of functions.
• hello(sys.argv[2]) needs to be indented since it is inside an if statement.
• hello has 2 arguments so you need to call 2 arguments.
• as far as calling the function from terminal, you need to call python .py ...

The code should look like this:

import sys
def hello(a, b):
    print "hello and that's your sum:"
    sum = a+b
    print sum

if __name__== "__main__":
    hello(int(sys.argv[1]), int(sys.argv[2]))

Then run the code with this command:

python hello.py 1 1

Answer 4

I found this thread looking for information about dealing with parameters; this easy guide was so cool:

import argparse

parser = argparse.ArgumentParser(description='Script so useful.')
parser.add_argument("--opt1", type=int, default=1)
parser.add_argument("--opt2")

args = parser.parse_args()

opt1_value = args.opt1
opt2_value = args.opt2

run like:

python myScript.py --opt2 = 'hi'

Answer 5

Your indentation is broken. This should fix it:

import sys

def hello(a,b):
    print 'hello and thats your sum:'
    sum=a+b
    print sum

if __name__ == "__main__":
    hello(sys.argv[1], sys.argv[2])

Obviously, if you put the if __name__ statement inside the function, it will only ever be evaluated if you run that function. The problem is: the point of said statement is to run the function in the first place.

Answer 6

import sys

def hello(a, b):
    print  'hello and that\'s your sum: {0}'.format(a + b)

if __name__ == '__main__':
    hello(int(sys.argv[1]), int(sys.argv[2]))

Moreover see @thibauts answer about how to call python script.

Answer 7

There are more than a couple of mistakes in the code.

1. 'import sys' line should be outside the functions as the function is itself being called using arguments fetched using sys functions.
2. If you want correct sum, you should cast the arguments (strings) into floats. Change the sum line to --> sum = float(a) + float(b).

3. Since you have not defined any default values for any of the function arguments, it is necessary to pass both arguments while calling the function --> hello(sys.argv[2], sys.argv[2])

   import sys def hello(a,b): print ("hello and that's your sum:") sum=float(a)+float(b) print (sum)

   if __name__ == "__main__": hello(sys.argv[1], sys.argv[2])

Also, using "C:\Python27>hello 1 1" to run the code looks fine but you have to make sure that the file is in one of the directories that Python knows about (PATH env variable). So, please use the full path to validate the code. Something like:

C:\Python34>python C:\Users\pranayk\Desktop\hello.py 1 1