Syntax and Usage

Now that you're familiar with file input and output, read this for more on syntax and usage.

Files: Writing to Files

Let's first see how to write to a file:

Type in the following in the Python Shell:

>>> myOut = open("out.txt", 'w')
>>> myOut.write("Hello, my name is Fran.\n")
>>> myOut.write("I like to dance ")
>>> myOut.write("and sing.")
>>> myOut.close()

Let's try to find the file we just created:

Open the folder containing all the programs you worked on today.

Or, do the following:

>>> myOut = open("out.txt")
>>> print(myOut.read())
>>> myOut.close()

We can add more to the file that already exists:

Type in the following in the Python Shell:

>>> myOut = open("out.txt",'a')
>>> myOut.write("I went to the circus today.")
>>> myOut.close()

Then find the file and see how it changed. Or, do the following:

>>> myOut = open("out.txt")
>>> print(myOut.read())
>>> myOut.close()

You can find this program in the file workWithFiles5.py

Methods for writing to a file

Method	Description
open(<filename>, 'w') open(<filename>, 'a')	open the file for writing ('w') or appending ('a')
write(<text>)	writes a string <text> to a file

Example: Let's ask the user to enter a positive integer n and a file name, create a file with the given file name and put the squares of the first n positive integers into it, separated by space.

  n = int(input("Enter a positive integer:"))
if n > 0:
    fname = input("Please enter a file name:")
    output = open(fname + ".txt",'w')
    for i in range(1,n+1):
    output.write(str(i*i)+' ')
    output.close()
    print("Done! Look for the file",fname+'.txt')
else:
    print("positive integer is expected!")

You can find this program in the file workWithFiles6.py