From the doc,
Modes 'r+', 'w+' and 'a+' open the file for updating (note that 'w+' truncates the file). Append 'b' to the mode to open the file in binary mode, on systems that differentiate between binary and text files; on systems that don’t have this distinction, adding the 'b' has no effect.
w+ : Opens a file for both writing and reading. Overwrites the existing file if the file exists. If the file does not exist, creates a new file for reading and writing.
Let's say you're opening the file with a
with statement like you should be. Then you'd do something like this to read from your file:
with open('somefile.txt', 'w+') as f: # Note that f has now been truncated to 0 bytes, so you'll only # be able to read data that you wrote earlier... f.write('somedata\n') f.seek(0) # Important: return to the top of the file before reading, otherwise you'll just read an empty string data = f.read() # Returns 'somedata\n'
f.seek(0) -- if you forget this, the
f.read() call will try to read from the end of the file, and will return an empty string.