- Expression statements
- The pass statement
- The del statement
- The return statement
- The import statement
- The continue and break statement
What is a statement in Python?
A statement is an instruction that a Python interpreter can execute. So, in simple words, we can say anything written in Python is a statement.
Python statement ends with the token NEWLINE character. It means each line in a Python script is a statement.
For example, a = 10 is an assignment statement. where a is a variable name and 10 is its value. There are other kinds of statements such as if statement, for statement, while statement, etc., we will learn them in the following lessons.
There are mainly four types of statements in Python, print statements, Assignment statements, Conditional statements, Looping statements.
The print and assignment statements are commonly used. The result of a print statement is a value. Assignment statements don’t produce a result it just assigns a value to the operand on its left side.
A Python script usually contains a sequence of statements. If there is more than one statement, the result appears only one time when all statements execute.
Example
# statement 1 print('Hello') # statement 2 x = 20 # statement 3 print(x) Code language: Python (python)Output
Hello 20
As you can see, we have used three statements in our program. Also, we have added the comments in our code. In Python, we use the hash ( # ) symbol to start writing a comment. In Python, comments describe what code is doing so other people can understand it.
We can add multiple statements on a single line separated by semicolons, as follows:
# two statements in a single l = 10; b = 5 # statement 3 print('Area of rectangle:', l * b) # Output Area of rectangle: 50Code language: Python (python)Multi-Line Statements
Python statement ends with the token NEWLINE character. But we can extend the statement over multiple lines using line continuation character ( \ ). This is known as an explicit continuation.
Example
addition = 10 + 20 + \ 30 + 40 + \ 50 + 60 + 70 print(addition) # Output: 280 Code language: Python (python)Implicit continuation:
We can use parentheses () to write a multi-line statement. We can add a line continuation statement inside it. Whatever we add inside a parentheses () will treat as a single statement even it is placed on multiple lines.
Example:
addition = (10 + 20 + 30 + 40 + 50 + 60 + 70) print(addition) # Output: 280Code language: Python (python)As you see, we have removed the the line continuation character ( \ ) if we are using the parentheses () .
We can use square brackets [] to create a list. Then, if required, we can place each list item on a single line for better readability.
Same as square brackets, we can use the curly < >to create a dictionary with every key-value pair on a new line for better readability.
Example:
# list of strings names = ['Emma', 'Kelly', 'Jessa'] print(names) # dictionary name as a key and mark as a value # string:int students = 'Emma': 70, 'Kelly': 65, 'Jessa': 75> print(students)Code language: Python (python)Output:
['Emma', 'Kelly', 'Jessa']Python Compound Statements
Compound statements contain (groups of) other statements; they affect or control the execution of those other statements in some way.
The compound statement includes the conditional and loop statement.
- if statement: It is a control flow statement that will execute statements under it if the condition is true. Also kown as a conditional statement.
- while statements: The while loop statement repeatedly executes a code block while a particular condition is true. Also known as a looping statement.
- for statement: Using for loop statement, we can iterate any sequence or iterable variable. The sequence can be string, list, dictionary, set, or tuple. Also known as a looping statement.
- try statement: specifies exception handlers.
- with statement: Used to cleanup code for a group of statements, while the with statement allows the execution of initialization and finalization code around a block of code.
Simple Statements
Apart from the declaration and calculation statements, Python has various simple statements for a specific purpose. Let’s see them one by one.
If you are an absolute beginner, you can move to the other beginner tutorials and then come back to this section.
Expression statements
Expression statements are used to compute and write a value. An expression statement evaluates the expression list and calculates the value.
To understand this, you need to understand an expression is in Python.
An expression is a combination of values, variables, and operators. A single value all by itself is considered an expression. Following are all legal expressions (assuming that the variable x has been assigned a value):
5 x x + 20Code language: Python (python)If your type the expression in an interactive python shell, you will get the result.
So here x + 20 is the expression statement which computes the final value if we assume variable x has been assigned a value (10). So final value of the expression will become 30.
But in a script, an expression all by itself doesn’t do anything! So we mostly assign an expression to a variable, which becomes a statement for an interpreter to execute.
Example:
x = 5 # right hand side of = is a expression statement # x = x + 10 is a complete statement x = x + 10Code language: Python (python)The pass statement
pass is a null operation. Nothing happens when it executes. It is useful as a placeholder when a statement is required syntactically, but no code needs to be executed.
For example, you created a function for future releases, so you don’t want to write a code now. In such cases, we can use a pass statement.
Example:
# create a function def fun1(arg): pass # a function that does nothing (yet) Code language: Python (python)The del statement
The Python del statement is used to delete objects/variables.
Syntax:
del target_listCode language: Python (python)The target_list contains the variable to delete separated by a comma. Once the variable is deleted, we can’t access it.
Example:
x = 10 y = 30 print(x, y) # delete x and y del x, y # try to access it print(x, y)Code language: Python (python)Output:
10 30 NameError: name 'x' is not defined
The return statement
We create a function in Python to perform a specific task. The function can return a value that is nothing but an output of function execution.
Using a return statement, we can return a value from a function when called.
# Define a function # function acceptts two numbers and return their sum def addition(num1, num2): return num1 + num2 # return the sum of two numbers # result is the return value result = addition(10, 20) print(result) Code language: Python (python)Output:
The import statement
The import statement is used to import modules. We can also import individual classes from a module.
Python has a huge list of built-in modules which we can use in our code. For example, we can use the built-in module DateTime to work with date and time.
Example: Import datetime module
import datetime # get current datetime now = datetime.datetime.now() print(now)Code language: Python (python)2021-08-30 18:30:33.103945
The continue and break statement
- break Statement: The break statement is used inside the loop to exit out of the loop.
- continue Statement: The continue statement skip the current iteration and move to the next iteration.
We use break, continue statements to alter the loop’s execution in a certain manner.
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