python file io code example

Example 1: python file open modes

r for reading
r+ opens for reading and writing (cannot truncate a file)
w for writing
w+ for writing and reading (can truncate a file)
rb for reading a binary file. The file pointer is placed at the beginning of the file.
rb+ reading or writing a binary file
wb+ writing a binary file
a+ opens for appending
ab+ Opens a file for both appending and reading in binary. The file pointer is at the end of the file if the file exists. The file opens in the append mode.
x open for exclusive creation, failing if the file already exists (Python 3)

Example 2: python write to file

with open(filename,"w") as f:
  f.write('Hello World')

Example 3: python file open

#there are many modes you can open files in. r means read.
file = open('C:\Users\yourname\files\file.txt','r')
text = file.read()

#you can write a string to it, too!
file = open('C:\Users\yourname\files\file.txt','w')
file.write('This is a typical string')

#don't forget to close it afterwards!
file.close()

Example 4: python3 seek

>>> f = open('workfile', 'rb+')
>>> f.write(b'0123456789abcdef')
16
>>> f.seek(5)      # Go to the 6th byte in the file
5
>>> f.read(1)
b'5'
>>> f.seek(-3, 2)  # Go to the 3rd byte before the end
13
>>> f.read(1)
b'd'

Example 5: python write to file

with open("testfile.txt", "w") as f:
  # "w" - write into file
  # "r" - read into file
  # "+" - read and write into file
  f.write("Hello World")

Example 6: with open as file python

>>> with open('workfile') as f:
...     read_data = f.read()

>>> # We can check that the file has been automatically closed.
>>> f.closed
True