File Open Function with Try & Except Python 2.7.1

You'll need to indent the return 0 if you want to return from within the except block. Also, your argument isn't doing much of anything. Instead of assigning it the filehandle, I assume you want this function to be able to test any file? If not, you don't need any arguments.

def FileCheck(fn):
    try:
      open(fn, "r")
      return 1
    except IOError:
      print "Error: File does not appear to exist."
      return 0

result = FileCheck("testfile")
print result

This is likely because you want to open the file in read mode. Replace the "U" with "r".

Of course, you can use os.path.isfile('filepath') too.

I think os.path.isfile() is better if you just want to "check" if a file exists since you do not need to actually open the file. Anyway, after open it is a considered best practice to close the file and examples above did not include this.