Python Code Block: Syntax, Usage, and Examples

In Python, a code block is a segment of code that belongs together and shares the same indentation level.

How to Use a Code Block in Python

Python uses indentation to define blocks of code. Each code block starts with an indentation and ends when the indentation level returns to a previous level.

                  

                    python
                    
                      
                    
                  
                  

                    if True:
    print("This is inside a code block.")
print("This is outside the code block.")

                  
                

When to Use Code Blocks in Python

Code blocks are essential in Python programs of any kind for defining the scope of control structures, functions, and loops. They help organize code into manageable segments.

If Statements

In if statements or other conditional statements, code blocks define the lines of code to execute when conditions evaluate to True.

                  

                    python
                    
                      
                    
                  
                  

                    age = 20
if age >= 18:
    print("Adult")  # This is a code block
else:
    print("Minor")  # This is another code block

                  
                

Functions

Every Python function uses a code block to contain its operations.

                  

                    python
                    
                      
                    
                  
                  

                    def greet():
    print("Hello, welcome!")  # Function's code block

                  
                

Loops

For loops execute code blocks as long as there are items in a sequence to iterate over. While loops execute code blocks as long as a specified condition is true.

                  

                    python
                    
                      
                    
                  
                  

                    for i in range(5):
    print(i)  # Loop's code block

                  
                

Examples of Code Blocks in Python

Nested If Statements

Code blocks can exist within other blocks. As an example, consider nested if statements.

                  

                    python
                    
                      
                    
                  
                  

                    x = 10
if x > 5:
    print("x is greater than 5")
    if x % 2 == 0:
        print("x is even")  # Nested code block

                  
                

Multiple Operations in Loops

Loops often feature multiple operations within their code blocks, executing more than one action per iteration.

                  

                    python
                    
                      
                    
                  
                  

                    for i in range(3):
    print(i)
    print(i*2)  # Multiple statements in a loop's code block

                  
                

Learn More About Code Blocks in Python

Importance of Indentation

Other programming languages use indentation only for readability. Code in Python, however, needs proper indentation to identify blocks of code. Incorrect indentation can lead to errors or unintended behavior.

                  

                    python
                    
                      
                    
                  
                  

                    if True:
print("Incorrect indentation")  # Causes IndentationError