Python Syntax
Python syntax refers to the set of rules that defines how a Python program is written and interpreted. Unlike many other programming languages, Python is designed to be highly readable, using English keywords where other languages use punctuation. Moreover, Python eschews the use of end-of-line semicolons and braces for block delimiters, relying instead on indentation to define the structure.
Indentation
Indentation is critical in Python and is used to define the blocks of code. Consistent spacing is essential, as inconsistent indentation can lead to errors or unexpected behavior. Typically, a block of code under a class, function definition, or control flow statement is indented by four spaces.
Example:
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def greet(name): if name: print("Hello, " + name + "!") else: print("Hello, World!") greet("Alice") greet("") |
In this example, both the if
statement and the else
statement are indented to indicate they are within the greet
function’s block. The print
statements are further indented to show they belong to their respective conditional blocks.
Variables
Variables in Python are created by assigning a value to a name. Python is dynamically typed, which means you don’t need to declare a variable’s type explicitly. The type is inferred from the value it is assigned, and a variable’s type can change if it is reassigned to a value of a different type.
Example:
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name = "John Doe" # String age = 30 # Integer height = 5.9 # Float is_student = True # Boolean # Reassigning a variable to a different type age = "Thirty" |
Comments
Comments in Python are marked with a #
symbol for single-line comments. Python does not execute the part of the line that comes after #
, allowing developers to include annotations or disable parts of the code temporarily. For multi-line comments, you can either use a #
on each line or triple quotes ("""
or '''
) to enclose the comment block, even though the latter is technically a multi-line string and not a comment by definition.
Example:
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# This is a single-line comment # The following variable stores the name of a user user_name = "Jane Doe" """ This is a multi-line comment (or string) used as a comment to describe the following block of code, which prints a greeting to the console. """ print("Hello, " + user_name + "!") |
Understanding these fundamental aspects of Python syntax is crucial for writing clear, readable, and efficient Python code. As you become more familiar with Python, you’ll appreciate its emphasis on readability and the simplicity of its syntax, which makes programming in Python both enjoyable and productive.