Reading and Writing Files

To open a file:

Let us look at the example first:

#
# Read and write files using the built-in Python file methods
#
def main():
   # Open a file for writing and create if it doesn't exist
   f = open("mytxtfile.txt", "w+")
   # Open the file for appending text to the end
   # write some lines of data to the file
   for i in range(5, 10):
       f.write("This is line number " + str(i) + "\r\n")
       # close the file when done
   f.close()

if __name__ == "__main__":
 main()

# Read and write files using the built-in Python file methods

def main():

# Open a file for writing and create if it doesn't exist

f = open("mytxtfile.txt", "w+")

# Open the file for appending text to the end

# write some lines of data to the file

for i in range(5, 10):

f.write("This is line number " + str(i) + "\r\n")

# close the file when done

f.close()

if __name__ == "__main__":

main()

f = open(“mytxtfile.txt”, “w+”) ; Argument filename to operate on
Kind of access to give W write permission and +
sign to create the file if it does not already exist

Read the file content:

def main():
    f = open("mytxtfile.txt", "r")
    if f.mode == 'r':
        contents = f.read()
        print(contents)

if __name__ == "__main__":
    main()

def main():

f = open("mytxtfile.txt", "r")

if f.mode == 'r':

contents = f.read()

print(contents)

if __name__ == "__main__":

main()

contents = f.read() is used to read a file content.

Read the file line by line.

If your file is large it is not a good idea to read the whole file at once so we can read the file line by line. We use readlines for this Let us look at the example

def main():
    f = open("mytxtfile.txt", "r")
    if f.mode == 'r':
        c = f.readlines()
    for a in c:
        print(a)

if __name__ == "__main__":
    main()

def main():

f = open("mytxtfile.txt", "r")

if f.mode == 'r':

c = f.readlines()

for a in c:

print(a)

if __name__ == "__main__":

main()