python reading and writing files code example

Example 1: python writing to text file

f = open("demofile2.txt", "a")
f.write("Now the file has more content!")
f.close()

#open and read the file after the appending:
f = open("demofile2.txt", "r")
print(f.read())

Example 2: python write to file

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

Example 3: python file reading

fin = open("NAME.txt", 'r')
body = fin.read().split("\n")
line = fin.readline().strip()

Example 4: read files and write into another files python

import sys
import glob
import os.path

list_of_files = glob.glob('/Users/Emily/Topics/*.txt') #500 files

for file_name in list_of_files:
    print(file_name)

    # This needs to be done *inside the loop*
    f= open(file_name, 'r')
    lst = []
    for line in f:
       line.strip()
       line = line.replace("\n" ,'')
       line = line.replace("//" , '')
       lst.append(line)
    f.close()

    f=open(os.path.join('/Users/Emily/UpdatedTopics',
    os.path.basename(file_name)) , 'w')

    for line in lst:
       f.write(line)
    f.close()

Example 5: python open and read file with

with open('pagehead.section.htm','r') as f:
    output = f.read()

Example 6: read and write file in python

#Write a Python program to create a file of numbers by taking input from the user and then display the content of the file. You can take input of non-zero numbers, with an appropriate prompt, from the user until the user enters a zero to create the file assuming that the numbers are non-zero.  
    f = open ('NumFile.txt','w')
    while True :
        no = int(input("enter a number (0 for exit)"))
        if no == 0 :
            print("you entered zero(0) ....... \n now you are exit  !!!!!!!!!!!")
            break
        else :
            f.write(str(no)+"\n")
    f.close() 
    f1 = open ('NumFile.txt','r')
    print("\ncontent of file :: \n",f1.read())
    f1.close()