Python_Fundamentals

• Variables
• Type Conversion
• Comments
• Input
• Operators
• String Formatting
• .2f, .1f, .3f
• print() with comma
• print() with +
• f-strings

# Python Fundamentals Cheat Sheet

A beginner-friendly reference for Python basics with examples.


## 1. Variables

Variables are used to store values.

```python
name = "Alice"
age = 25
height = 5.4

• Strings use quotes: "text" or 'text'
• Integers and floats do not use quotes

2. Type Conversion

Python can convert between types using int(), float(), and str().

age = "25"
age_int = int(age)        # Converts to integer
height = 5
height_str = str(height)  # Converts to string

3. Comments

Use comments to explain code:

# This is a single-line comment

'''
This is a
multi-line comment
'''

4. Input

The input() function reads user input as a string.

name = input("What is your name? ")
print("Hello,", name)

Convert input to a number if needed:

age = int(input("Enter your age: "))

5. Operators

Type	Operator	Example
Arithmetic	+ - * / // % **	a + b, a ** b
Assignment	= += -= *=	x += 1
Comparison	== != > < >= <=	x == y
Logical	and or not	x > 5 and x < 10

Example:

a = 10
b = 3
print(a + b)  # 13
print(a % b)  # 1

6. String Formatting

Old Style

name = "Alice"
age = 25
print("Name: %s, Age: %d" % (name, age))

str.format()

pi = 3.14159
print("Value of pi is {:.2f}".format(pi))  # 2 decimal places

• .2f = 2 decimal places
• .1f = 1 decimal place
• .3f = 3 decimal places

f-strings (Python 3.6+)

name = "Bob"
score = 91.235
print(f"Name: {name}, Score: {score:.2f}")  # Score: 91.24

7. Print with Comma ,

Using commas in print() separates values with a space and auto-converts types.

name = "Alice"
age = 30
print("Name:", name, "Age:", age)

Output:

Name: Alice Age: 30

8. Print with + (Concatenation)

You must convert non-strings using str().

name = "Bob"
age = 28
print("Name: " + name + ", Age: " + str(age))

9. f-Strings Summary

name = "Sam"
salary = 1234.5678

print(f"Name: {name}")
print(f"Salary (2 decimal): {salary:.2f}")
print(f"Salary (3 decimal): {salary:.3f}")
print(f"Salary (1 decimal): {salary:.1f}")

10. Conditional Statements (if, elif, else)

Use if statements to make decisions in your program.

age = int(input("Enter your age: "))

if age >= 18:
    print("You are an adult.")
elif age >= 13:
    print("You are a teenager.")
else:
    print("You are a child.")

KEY IDEAS

• Variables store data
• Input gives user data (as string)
• Use int(), float(), str() for conversions
• Use comments (#, ''') to explain code
• Use print() with ,, +, or f"" for output
• Use .2f, .1f, etc. for formatting floats

Happy Coding!