Why is Indentation Important in Python?

Indentation in Python is a crucial syntax element that defines a code block, which is a group unit of code execution.

Unlike other programming languages that use curly braces { } or semicolon ; to indicate the start and end of a code block, Python uses indentation to separate code blocks.

Typically, indentation is done using 4 spaces or a tab to delineate the code execution units.

In most programming languages, indentation is used to improve code readability; however, in Python, incorrect indentation results in a syntax error.

Indentation is used to define code blocks in Python. The following are some examples of how indentation is used.

Python uses the if and else keywords to define conditional statements.

A Keyword is a term that has a special meaning within a program.

The if keyword defines the code block executed when the condition is true, and the else keyword defines the code block executed when the condition is false.

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if condition:
    print("Condition is True")  # Indentation
else:
    print("Condition is False") # Indentation

Python defines functions that perform specific tasks using the def keyword.

The code below defines a function called multiply, which returns the product of two numbers a and b using the return keyword.

Unlike everyday arithmetic, multiplication in programming is represented by the asterisk symbol * instead of the letter x.

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def multiply(a, b):
    # Define the function body with indentation
    result = a * b
    return result # Define the return value with indentation

print(multiply(3, 5)) # Outputs 15

print(multiply(4, 6)) # Outputs 24

The function defined as multiply can be called multiple times within the program, as shown with multiply(3, 5) and multiply(4, 6).

Using functions in this way reduces code duplication by allowing code reuse.

Loops are executed repeatedly while a specific condition is true and are defined using the for or while keywords.

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for i in range(4): # Loops 4 times from 0 to 3
    print(i)       # Indent the block of code that repeats

• for is the keyword that defines a loop, while i in range(4) specifies the range of repetition.

• The indented code block beneath the colon (:) defines the code to execute for each loop iteration. In the example, print(i) outputs the value of i for each loop.

• i is the loop's variable, incrementing sequentially from 0 to 3. Each loop iteration increases i by 1.

• range is a function that generates a sequence of numbers; range(4) generates numbers from 0 to 3.

• The loop in the example executes print(i) when i is 0, 1, 2, and 3, outputting 0, 1, 2, and 3.

• Typically, 4 spaces or 1 tab are used for indentation.

• All lines of code within the same block should be indented at the same level. In the code example below, if and else are at the same conditional level, and therefore, they share the same level of indentation.

• Nested code blocks receive additional indentation. For example, in the example code below, the print function inside the if block is indented one more level.

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def greet(name):
    # Indent to separate the function body
    # Conditional block executed if a name is provided
    if name:
        # Further indent code within the if block
        print("Name:", name)

    # Conditional block executed if no name is provided
    # Use the same level of indentation as if for else
    else:
        print("Hello.")

greet("CodeFriends")
# Outputs "Name: CodeFriends"