python with open file code example

Example 1: python read file line by line

with open("file.txt") as file_in:
    lines = []
    for line in file_in:
        lines.append(line)

Example 2: python read file

with open("file.txt", "r") as txt_file:
  return txt_file.readlines()

Example 3: python write to file

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

Example 4: python open file

with open('filename', 'a') as f: # able to append data to file
	f.write(var1) # Were var1 is some variable you have set previously
	f.write('data') 
	f.close() # You can add this but it is not mandatory 

with open('filename', 'r') as f: # able to read data from file ( also is the default mode when opening a file in python)

with open('filename', 'x') as f: # Creates new file, if it already exists it will cause it to fail

with open('filename', 't') as f: # opens the file in text mode (also is defualt)

with open('filename', 'b') as f: # Use if your file will contain binary data
  
with open('filename', 'w') as f: # Open file with ability to write, will also create the file if it does not exist (if it exists will cause it to fail)
  
with open('filename', '+') as f: # Opens file with reading and writing

# You can combine these as you like with the + for reading and writing

Example 5: python with file.open

# Reference https://docs.python.org/3/library/functions.html#open

# Method 1
file = open("welcome.txt", "r") # mode can be r(read) w(write) and others 
data = file.read()
file.close()

# Method 2 - automatic close
with open("welcome.txt") as infile:
  data = file.read()

Example 6: python write to file

path = "guide/README.txt" # The path of your file should go here
with open(path, "w") as fil: # Opens the file using 'w' method. See below for list of methods.
  fil.write("This is the README. It is reccomended that you read it.") # Writes to the file used .write() method
  fil.close() # Closes file
'''
List of methods:
w* - replace everything with needed text
r^ - read the file
a* - adds to file
x - creates file

* Creates file if the file at that path does not exist
^ Throws error if file does not exist
'''