Key Features of Python Syntax
Indentation Instead of Braces:
Python uses indentation to define blocks of code, unlike many programming languages that use curly braces { }.
Example:
# Using indentation for a block of code
if True:
print("This is indented correctly!")
Incorrect Example:
if True:
print("This will cause an error!") # Missing indentation
Case Sensitivity:
Python is case-sensitive, which means Variable and variable are treated as different identifiers.
Example:
name = "Alice"
Name = "Bob"
print(name) # Outputs: Alice
print(Name) # Outputs: Bob
No Semicolons:
In Python, you don’t need to end statements with semicolons ( ; ). Python automatically understands the end of a statement based on line breaks.
Example:
print("Hello, World!") # No semicolon needed
However, you can use a semicolon to separate multiple statements on the same line, though it’s not recommended for readability.
print("Hello"); print("World") # Works, but not recommended
Comments in Python:
Comments are used to explain code and are ignored by the Python interpreter.
- Single-Line Comment: Use #.
# This is a single-line comment
print("Comments are ignored by the interpreter.")
- Multi-Line Comments: Use triple quotes.
"""
This is a multi-line comment.
It can span multiple lines.
"""
print("Multi-line comments are useful for documentation.")
Writing Variables and Data Types
In Python, variables don’t require explicit declaration. You simply assign a value to a variable, and Python determines its type dynamically.
Example:
# Assigning values to variables
x = 10 # Integer
y = 3.14 # Float
name = "John" # String
print(x, y, name)
Output:
10 3.14 John
Input and Output Syntax
Output Using print():
The print() function displays output to the screen.
print("Hello, Python!") # Outputs: Hello, Python!
Taking User Input:
Use the input() function to take input from the user.
user_name = input("Enter your name: ")
print("Welcome, " + user_name + "!")
Example Output:
Enter your name: Alice
Welcome, Alice!
Python Statements
Single-Line Statement:
A single action written in one line.
print("This is a single-line statement.")
Multi-Line Statement:
Use a backslash (\) to continue a statement on the next line.
result = 10 + 20 + 30 + \
40 + 50
print(result)
Output:
150
Python Indentation Rules
- Indent Consistently: Python recommends using four spaces per indentation level.
- Avoid Mixing Tabs and Spaces: Mixing tabs and spaces for indentation will raise an error.
Example:
def greet():
print("Hello!") # Proper indentation
greet()
Python Syntax with Conditional Statements
Python uses if, elif, and else for conditional logic.
Example:
age = 18
if age < 18:
print("You are a minor.")
elif age == 18:
print("You just became an adult!")
else:
print("You are an adult.")
Output:
You just became an adult!
Loops in Python Syntax
For Loop:
for i in range(5):
print(i)
Output:
0
1
2
3
4
While Loop:
count = 0
while count < 3:
print(count)
count += 1
Output:
0
1
2