Python Statements

In this tutorial, you will learn Python statements. Also, you will learn simple statements and compound statements.

Multi-Line Statements
Python Compound Statements
Simple Statements
- 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)

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: 50

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

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: 280

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)

Output:

['Emma', 'Kelly', 'Jessa']
{'Emma': 70, 'Kelly': 65, 'Jessa': 75}

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 + 20

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 + 10

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)

The `del` statement

The Python del statement is used to delete objects/variables.

Syntax:

del target_list

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)

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.

Example:

# 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)

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)

Output:

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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