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Strings

So far, we have already stored some text in a variable. For example "Hello World!" which is called a string. A string is a primitive data type. Integer, float, boolean and None are also primitive data types which we will cover later.

A string is simply a series of characters. Anything inside quotes is considered a string in Python, and you can use single (') or double quotes (") around your strings like this:

text = "This is a string."
another_text = 'This is also a string.'

This flexibility allows you to use quotes and apostrophes within your strings:

text = "One of Python's strengths is its diverse and supportive community."
print(text)
>>> Output
One of Python's strengths is its diverse and supportive community.

text = 'I told my friend, "Python is my favorite language!"'
print(text)
>>> Output
I told my friend, "Python is my favorite language!"

type()

Let's check the type of the variable text.

text = "The language 'Python' is named after Monty Python, not the snake."
print(type(text))
>>> Output
<class 'str'>

type() comes in handy to check the type of variables. In this case, we can verify that text is indeed a string. Just like print(), type() is an important tool in your programming arsenal.

Info

It is advisable to consistently enclose your strings with either single '...' or double quotes "...". This will make your code easier to read and maintain.

String methods

One of the simplest string manipulation, is to change the case of the words in a string.

name = "paul atreides"
print(name.title())
>>> Output
Paul Atreides

A method is an action performed on an object (in our case the variable). The dot (.) in name.title() tells Python to make the title() method act on the variable name which holds the value "paul atreides".

Every method is followed by a set of parentheses, because methods often need additional information to do their work. That information is provided inside the parentheses. The title() method doesn’t need any additional information, so its parentheses are empty.

Methods vs. functions

We have already encountered functions like print() and type(). Functions are standalone entities that perform a specific task.

On the other hand, methods are associated with objects. In this case, the title() method is associated with the string object name.

String methods

You start with the variable input_string that holds the value "fEyD rAuThA". 

input_string = "fEyD rAuThA"

Experiment and apply a combination of the following methods:

  • capitalize()
  • title()
  • istitle()
  • isupper()
  • upper()
  • lower()

Eventually you should end up with the string "Feyd Rautha", print it.

Concatenation

It’s often useful to combine strings. For example, you might want to store first and last name in separate variables, and then combine them when you want to display someone’s full name.

Python uses the plus symbol (+) to combine strings. In this example, we use + to create a full name by combining a first_name, a space, and a last_name:

first_name = "paul"
last_name = "atreides"
full_name = first_name + " " + last_name
print(full_name)
>>> Output
paul atreides

Here, the full name is used in a sentence that greets the user, and the title() method is used to format the name appropriately. This code returns a simple but nicely formatted greeting:

full_name = "paul atreides"
print("Hello, " + full_name.title() + "!")
>>> Output
Hello, Paul Atreides!

Another way to nicely format strings is by using f-strings. To achieve the same result as above, simply put an f"..." in front of the string and use curly braces {} to insert the variables. 

full_name = "Alia Atreides"

print(f"Hello, {full_name}!")

# you can even apply methods directly to the variables 
# (within the curly braces)
print(f"Hello, {full_name.lower()}!")
>>> Output
Hello, Alia Atreides!
Hello, alia atreides!
A quote

Find a quote from a famous person you admire. Store the quote and name in variables and print both with an f-string.

Your output should look something like the following, including the quotation marks:

Frank Herbert (Dune opening quote): "I must not fear. Fear is the mind-killer."

Recap

This section was all about strings, we have covered:

  • How to create strings
  • Use type() to check a variable's type
  • String methods, such as title() and lower()
  • Distinction between methods and functions
  • String concatenation with + and f-strings (f"...")

Next, up we will introduce numbers in Python, namely integers and floats.