newbie question; output from simple print statement

[epost2]

Can someone explain to me the output of this simple script? I wonder
why ['test1.txt'] is printed before "files in c:\", and also why None
shows up?

________________
in file test.py:

def main():

print "files in c:\ :%s" % ListFiles("c:\")

def ListFiles(path):
for root,dirs,files in os.walk(path):
print files

if __name__ == "__main__":
main():

________________
output:

C:\> python test.py
['test1.txt']
files in c:\ :None

 

[Paul Watson]

Can someone explain to me the output of this simple script? I wonder
why ['test1.txt'] is printed before "files in c:\", and also why None
shows up?

________________
in file test.py:

def main():

print "files in c:\ :%s" % ListFiles("c:\")

def ListFiles(path):
for root,dirs,files in os.walk(path):
print files

if __name__ == "__main__":
main():

________________
output:

C:\> python test.py
['test1.txt']
files in c:\ :None

The function ListFiles() is being called first. This produces the
result that will be used to replace the %s of the print statement. In
this case, the return value is None, so nothing is printed.

How to Think Like a Computer Scientist
http://www.ibiblio.org.obp/thinkCSpy/

 

[epost2]

thanks.