Files in Python

In the blog about counting words, I used the funtion open() to coun the words in that file but I haven’t made a post explaining how to do that, so here it is:

In Python, you don’t need to import any library to read and write files.

The first step is to get a file object.

The way to do this is to use the open function.

A file is usually categorized as either text or binary.

A text file is often structured as a sequence of lines and a line is a sequence

of characters.

The line is terminated by a EOL (End Of Line) character.

The backslash character indicates that the next character will be treated as a

newline.

A binary file is basically any file that is not a text file. Binary files can

only be processed by application that know about the file’s structure.

To open a file for writing use the built-i open() function. open() returns a

file object, and is most commonly used with two arguments.

 

The syntax is:

file_object = open(filename, mode) where file_object is the variable to put the

file object.

 

The second argument describes the way in which the file will be used

The mode argument is optional; ‘r’ will be assumed if it’s omitted.

The modes can be:

‘r’ when the file will only be read

‘w’ for only writing (an existing file with the same name will be erased)

‘a’ opens the file for appending; any data written to the file is automatically

added to the end.

‘r+’ opens the file for both reading and writing.

Create a text file

Let’s first create a new text file. You can name it anything you like,

in this example we will name it “newfile.txt”.

file = open(“newfile.txt”, “w”)

file.write(“hello world in the new file

“)

file.write(“and another line

“)

file.close()

How to read a text file

To read a file, we can use different methods.

file.read( )

If you want to return a string containing all characters in the file, you can

use file.read().

file = open(‘newfile.txt’, ‘r’)

print file.read()

Output:

hello world in the new file

and another line

A video that explains it:

Thanks for reading.

Follow me on twitter: @danigguemez

#TC101 #python #files

Sources:http://www.pythonforbeginners.com/files/reading-and-writing-files-in-python

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