How to write to text file in python? - python-3.x

Question

I am a beginner in using python. I have created a plain text file and have to encrypt it to output file. But I am getting an error as below and unable to write it to output file. The code is running but the output file which should be encrypted is created.
#!/usr/bin/env python3
import os
import binascii
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.primitives import padding
from cryptography.hazmat.backends import default_backend
import argparse
def readfile_binary(file):
with open(file, 'rb') as f:
content = f.read()
return content
def writefile_binary(file, content):
with open(file, 'wb') as f:
f.write(content)
def main():
parser = argparse.ArgumentParser(description = 'Encryption and Decryption of the file')
parser.add_argument('-in', dest = 'input', required = True)
parser.add_argument('-out', dest = 'output', required = True)
parser.add_argument('-K', dest = 'key', help = 'The key to be used for encryption must be in hex')
parser.add_argument('-iv', dest = 'iv', help = 'The inintialisation vector, must be in hex')
args = parser.parse_args()
input_content = readfile_binary(args. input)
output_content = writefile_binary(args. output)
if __name__ == "__main__":
main()
The output file should be encrypted and it should be available in the directory.

Answer 1

These two lines:
input_content = readfile_binary(args. input)
output_content = writefile_binary(args. output)
There should not be a space in args.input. Here is an example,
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('filename')
args = parser.parse_args()
# using type hints can help reasoning about code
def write(filename: str, content: str) -> None:
with open(filename, 'wb') as f:
f.write(str.encode(content))
# if the filename was successfully parsed from stdin
if args.filename == 'filename.txt':
print(f"args: {args.filename}")
# write to the appropriate output file
write(filename=args.filename, content="content")

Answer 2

You might need to correct your code's indentation. Python requires indenting code within each function definition, loop, etc.
And as eric points out, there should be no spaces after the periods in args. input and args. output. Change those to args.input and args.output instead.
So:
#!/usr/bin/env python3
import os
import binascii
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.primitives import padding
from cryptography.hazmat.backends import default_backend
import argparse
def readfile_binary(file):
with open(file, 'rb') as f:
content = f.read()
return content
def writefile_binary(file, content):
with open(file, 'wb') as f:
f.write(content)
def main():
parser = argparse.ArgumentParser(description = 'Encryption and Decryption of the file')
parser.add_argument('-in', dest = 'input', required = True)
parser.add_argument('-out', dest = 'output', required = True)
parser.add_argument('-K', dest = 'key', help = 'The key to be used for encryption must be in hex')
parser.add_argument('-iv', dest = 'iv', help = 'The inintialisation vector, must be in hex')
args = parser.parse_args()
input_content = readfile_binary(args.input)
output_content = writefile_binary(args.output)
if __name__ == "__main__":
main()