How do I create a incrementing filename in Python?

Question

I\'m creating a program that will create a file and save it to the directory with the filename sample.xml. Once the file is saved when i try to run the program again it over

Answer 1

The two ways to do it are:

1. Check for the existence of the old file and if it exists try the next file name +1
2. save state data somewhere

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an easy way to do it off the bat would be:

import os.path as pth
filename = "myfile"
filenum = 1
while (pth.exists(pth.abspath(filename+str(filenum)+".py")):
    filenum+=1
my_next_file = open(filename+str(filenum)+".py",'w')

as a design thing, while True slows things down and isn't a great thing for code readability

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edited: @EOL contributions/ thoughts

so I think not having .format is more readable at first glance - but using .format is better for generality and convention so.

import os.path as pth
filename = "myfile"
filenum = 1
while (pth.exists(pth.abspath(filename+str(filenum)+".py")):
    filenum+=1
my_next_file = open("{}{}.py".format(filename, filenum),'w')
# or 
my_next_file = open(filename + "{}.py".format(filenum),'w')

and you don't have to use abspath - you can use relative paths if you prefer, I prefer abs path sometimes because it helps to normalize the paths passed :).

import os.path as pth
filename = "myfile"
filenum = 1
while (pth.exists(filename+str(filenum)+".py"):
    filenum+=1
##removed for conciseness