Python Variables and Data Types: Declaration and Assignment

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Questions and Answers

Which keyword is used in Python to assign a value to a variable?

var

declare

set

= (correct)

What is the maximum value that can be assigned to an integer variable in Python?

18446744073709551615

9223372036854775807 (correct)

32767

2147483647

Which one of these is a valid variable name in Python?

has_0_in_it (correct)

What is the output of the following Python code?`x = 9y = X*5print(y)`

NameError: name 'X' is not defined Signup and view all the answers

Which of the following data types can be assigned to a variable in Python?

All of the above Signup and view all the answers

What is the purpose of the `None` data type in Python?

To represent a missing or unknown value Signup and view all the answers

What is the result of the expression `True + True`?

1 Signup and view all the answers

Which of the following is an ordered collection of values of any type?

tuple Signup and view all the answers

What is the result of the expression `not False`?

True Signup and view all the answers

Which of the following is a valid complex number in Python?

2 + 1j Signup and view all the answers

What is the data type of the string `'hello'` in Python 3.x?

str Signup and view all the answers

What is the result of the expression `False and True`?

False Signup and view all the answers

What will be the output of the code snippet: a, b, c = 1, 2, 3?

1 2 3 Signup and view all the answers

What is the reason for the 'ValueError: need more than 2 values to unpack' in the code snippet: a, b = 1, 2, 3?

Too many values assigned for unpacking Signup and view all the answers

In Python, what is necessary for multiple assignment of values to variables?

Matching number of variables to number of values assigned Signup and view all the answers

What will be the output of the code snippet: a = b = c = 1?

1 1 1 Signup and view all the answers

Which statement about Python variable assignment is true?

Variables can change their type during different assignments. Signup and view all the answers

What is used in Python to define control and loop constructs?

Indentation Signup and view all the answers

Which of the following is an example of an immutable data type in Python?

int Signup and view all the answers

In Python, which function is used to obtain interactive input from the user?

input() Signup and view all the answers

What will be the output of the following code snippet in Python 3.x? `x = input('Write a number:')`

'10' Signup and view all the answers

Which type conversion is necessary when using user input for mathematical operations to avoid errors?

str to float Signup and view all the answers

Which of the following statements about Python's indentation is correct?

Python requires the use of whitespace, including indentation, which contributes to its readability Signup and view all the answers

What symbol is used in Python to indicate the start of a code block?

A colon (:) Signup and view all the answers

Which of the following statements about Python's code blocks is true?

Code blocks in Python, such as functions and loops, have no ending identifiers Signup and view all the answers

What is the recommended number of spaces to use for indentation in Python?

4 spaces Signup and view all the answers

Which of the following is a built-in data type in Python?

All of the above Signup and view all the answers

What logical operations can be performed on boolean values in Python?

and, or, not Signup and view all the answers

Study Notes

Variables and Data Types

In Python, assign values to variables using the = operator, and no need to declare variables in advance or assign a data type to them.
Assigning a value to a variable declares and initializes the variable with that value.

Variable Declaration and Assignment Statements

Declare and initialize variables with values of different data types:
- Integers: a = 2, b = 9223372036854775807
- Floating points: pi = 3.14
- Strings: c = 'A', name = 'John Doe'
- Boolean: q = True
- Empty value or null data type: x = None

Rules for Naming Variables

Variables names must start with a letter or an underscore.
The remainder of the variable name may consist of letters, numbers, and underscores.
Names are case sensitive.

Boolean Data Type

Boolean values can be used in arithmetic operations, where True is treated as 1 and False is treated as 0.
Boolean values can be used in logical operations, such as and, or, and not.

Data Types

Numbers:
- int: integer numbers
- float: floating point numbers
- Complex numbers
Strings:
- str: a unicode string (Python 3.x)
- bytes: a byte string
Sequences and Collections:
- tuple: an ordered collection of n values of any type (n >= 0)
- list: a sequence of values
- set: an unordered collection of unique values
- dict: an unordered collection of key-value pairs

Determining the Data Type

Use the type() function to determine the data type of a variable.

Assigning Multiple Values to Multiple Variables

Assign multiple values to multiple variables using the =, with the same number of values as variables.
Use _ to ignore unwanted values when assigning multiple values to multiple variables.

Assigning a Single Value to Multiple Variables

Assign a single value to multiple variables simultaneously using the = operator.

Mutability and Immutability

Immutable data types: int, float, complex, str, tuple, frozenset
Mutable data types: bytearray, list, set, dict

User Input

Use the input() function to get input from the user.
The input is always of type str, which is important if you want the user to enter numbers.

Block Indentation

Python uses indentation to define control and loop constructs.
Use the colon symbol (:) and indentation to show where blocks of code begin and end.
Blocks start with a colon and then contain the indented lines below it.
Use 4 spaces for indentation; tabs are not recommended.

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Description

Learn about variables and data types in Python. Understand how to create variables and assign values using the = sign. No need to declare a variable in advance or assign a data type to it in Python.