To write to a file, we open it using the same instruction. However, since we are using the file to write, we replace the 'r' with 'w' which means "write" in a way that replaces the existing data.

myfile = open('names.txt', 'w')
myfile.write("David\n")
myfile.write("Eric\n")
myfile.write("Fran\n")
myfile.close()

This code replaces the contents of a file. Unlike the code we have run so far, a file is persisted on the computer or stored. When we turn the computer off and on again, the file will still be there and the contents will be

David
Eric
Fran

The key idea is this, A file is used to store data persistently. When we assign a value to a variable, we are working with data temporarily. If we want to store data and read it later, we need to use a file.

append

If we just want to append a new name to the list we change the operation from 'w' to 'a'

myfile = open('names.txt', 'a')
myfile.write("Gary\n")
myfile.close()

Newline

A quick note is the special character we used in the string when we write to a file. The \n is actually a single character which is a special instruction to the computer that means newline

Try removing the \n from myfile.write("Gary\n") or adding a few of them and see what the result is.

Even though we write \n, when we print the entire contents of the file, it doesn't print \n but instead goes to a newline.

However, sometimes things add the newline themselves. If you run the following, see the difference.

The print instruction adds a newline by default, which helpful in most cases.