str(string) class. For example, you can use the
rjustmethod to get a string which is right justified to a specified width. See
help(str)for more details.
seq[a:b]code starting from position
b. We can also provide a third argument that determines the step by which the slicing is done. The default step is
1because of which it returns a continuous part of the text. Giving a negative step, i.e.,
-1will return the text in reverse.
input()function takes a string as argument and displays it to the user. Then it waits for the user to type something and press the return key. Once the user has entered and pressed the return key, the
input()function will then return that text the user has entered.
fileclass and using its
writemethods appropriately to read from or write to the file. The ability to read or write to the file depends on the mode you have specified for the file opening. Then finally, when you are finished with the file, you call the
closemethod to tell Python that we are done using the file.
openmethod. We open (or create it if it doesn't already exist) this file by using the built-in
openfunction and specifying the name of the file and the mode in which we want to open the file. The mode can be a read mode (
'r'), write mode (
'w') or append mode (
'a'). We can also specify whether we are reading, writing, or appending in text mode (
't') or binary mode (
'b'). There are actually many more modes available and
help(open)will give you more details about them. By default,
open()considers the file to be a 't'ext file and opens it in 'r'ead mode.
writemethod of the file object to write our string variable
poemto the file and then we finally
readlinemethod in a loop. This method returns a complete line including the newline character at the end of the line. When an empty string is returned, it means that we have reached the end of the file and we 'break' out of the loop.
readlineoutput that this program has indeed written to and read from our new
picklewhich you can use to store any plain Python object in a file and then get it back later. This is called storing the object persistently.
openthe file in write binary mode and then call the
dumpfunction of the
picklemodule. This process is called pickling.
loadfunction of the
picklemodule which returns the object. This process is called unpickling.
NOTE: If you are using Python 2, and we want to be able to read and write other non-English languages, we need to use the
unicodetype, and it all starts with the character
io.openand then use the
encodingargument in the first open statement to encode the message, and then again in the second open statement when decoding the message. Note that we should only use encoding in the open statement when in text mode.
ubefore the string) like we have used above, we have to make sure that Python itself is told that our program uses UTF-8, and we have to put
# encoding=utf-8comment at the top of our program.