Posted on by Miro Boro

Literals

1. Literals are notations for representing some fixed values in code. Python has various types of literals – for example, a literal can be a number (numeric literals, e.g., 123), or a string (string literals, e.g., “I am a literal.”).

2. The binary system is a system of numbers that employs 2 as the base. Therefore, a binary number is made up of 0s and 1s only, e.g., 1010 is 10 in decimal.

Octal and hexadecimal numeration systems, similarly, employ 8 and 16 as their bases respectively. The hexadecimal system uses the decimal numbers and six extra letters.

3. Integers (or simply ints) are one of the numerical types supported by Python. They are numbers written without a fractional component, e.g., 256, or -1 (negative integers).

4. Floating-point numbers (or simply floats) are another one of the numerical types supported by Python. They are numbers that contain (or are able to contain) a fractional component, e.g., 1.27.

5. To encode an apostrophe or a quote inside a string you can either use the escape character, e.g., 'I\'m happy.', or open and close the string using an opposite set of symbols to the ones you wish to encode, e.g., "I'm happy." to encode an apostrophe, and 'He said "Python", not "typhoon"' to encode a (double) quote.

6. Boolean values are the two constant objects True and False used to represent truth values (in numeric contexts 1 is True, while 0 is False.

 

EXTRA

There is one more, special literal that is used in Python: the None literal. This literal is a so-called NoneType object, and it is used to represent the absence of a value. We’ll tell you more about it soon.

 

Exercise 1

What types of literals are the following two examples?

"Hello ", "007"

They’re both strings/string literals.

 

Exercise 2

What types of literals are the following four examples?

"1.5", 2.0, 528, False

The first is a string, the second is a numerical literal (a float), the third is a numerical literal (an integer), and the fourth is a boolean literal.

 

Exercise 3

What is the decimal value of the following binary number?

1011

It’s 11, because (2**0) + (2**1) + (2**3) = 11

 

Ex. 4

Which of the following print statements displays the integer decimal 1000 (one thousand) on the screen?

print(1_0_0_0)

print(1,000)

print(01000)

print(1_000)

Correct selection

print(1_0_0_0)

print(1_000)

  • The print(1_0_0_0) and print(1_000) statements are correct.. Starting with version 3.6, Python allows the use of underscores in numeric literals to increase their readability when they are very large.
  • print(1,000) is incorrect. It is equal to print(1, 0) and outputs 1 0 on the screen.
  • print(01000) is incorrect because in Python leading zeros in decimal integer literals are not allowed.

 

Ex. 5

What is the output of the following code snippet?

Correct answer

15

The loop counts the number of characters in the string str. The escape sequence \', representing the single quotation mark, is counted as a single character. Therefore, the total number of characters, including the space, is 15.
Ex. 6

What is the output of the following code snippet?


 

Correct answer

3 3 0.0

  • The int() function converts a number or string to an integer. If the number is a float, the function discards the decimal part.
  • The str() function converts a value to a string.
  • The float() function converts a number or string to a float, including 0.
  • By default, the print() function does not print quotation marks of a string:

    print(x, y, z) -> print(3, '3', 0.0) -> 3 3 0.0