Python strings

/ #Python


A string can be anything from a letter, to a word or a whole sentence.

In Python you can do many really cool things with the strings. Strings in Python is actually immutable, this means that after a string has been created, you can not change it. But instead you have to create new strings, based on the original. See examples below.

Basic example

>>> s = 'Hello'
>>> print(s)
s
>>> print(s + 'world') # Add two strings together
Helloworld
>>> print(s, 'world') # Another way of adding string together. The ',' adds an additional space.
Hello world
>>> print(s + str(10)) # If you are adding a string and a int together, remember to add str() around the int
Hello10
>>> print(len(s)) # Prints the length of your string
4

You can open up a Python interpreter and play around like this. Just open up a terminal or command line and type "python" and hit enter.

How to slice a string

Strings also come with the possibility to slice them. Here is some basic example of usage.

>>> s = 'python'
>>> s[0] # Letter number 0
'p'
>>> s[3] # Letter number 3
'h'
>>> s[3:4] # Everything between letter 3 and 4
'ho'
>>> s[2:] # All after letter number 2
'thon'
>>> s[:2] # All infront of letter number 2
'py'
>>> s[-1] # You can also go the other way, last character
'n'
>>> s[-2:] # Two last characters
'on'

As you can see there is a lot of ways to slice a string. If you play around, you will soon get hang of how it's working.

Other string methods

>>> s = 'Python'
>>> s.lower() # Makes whole string lowercase, you can use upper() to do the opposite.
'python'
>>> s.isalpha() # Will return true if all characters is alphanumeric.
True
>>> s.find('t') # Returns the index number where the string finds 't'
2
>>> s.startswith('P') # Returns true if the string starts with 'P'
True
>>> s = 'Python Programming'
>>> s.split()
['Python', 'Programming']

Now, that was a short introduction to strings. This is just a little bit of what Python strings can offer.

Exercises

1) Open up a Python interpreter and create a new string with the value "Programming"
-Slice and print the string to get this result: 'ogramming'
-Slice and print the string to get this result: 'ram'

2) Almost the same as exercise 1, but here I want you to slice a string and put it together.
-Slice, put them together and print the string to get this result: 'pro ing'
-Slice, put them together and print the string to get this result: 'pro mm ing'

Feel free to add your answer here. And as always, if there is anything you are wondering about. Feel free to post your question here!


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