Python Built-in Functions

🌟 Most Common Functions

print("Hello World!")
print(42)
print("Age:", 25)

len("Hello")      # 5
len([1, 2, 3])    # 3
len({"a": 1})     # 1

type(42)          # int
type("hi")        # str
type([1, 2])      # list

name = input("Your name: ")
age = input("Your age: ")
print(f"Hi {name}!")

🔹 Number Functions

Math Operations

# Find biggest and smallest
max(5, 2, 8, 1)    # 8
min(5, 2, 8, 1)    # 1

# Add all numbers
sum([1, 2, 3, 4])  # 10

# Absolute value (remove minus sign)
abs(-5)            # 5
abs(3)             # 3

Rounding Numbers

# Round to nearest whole number
round(3.7)         # 4
round(3.2)         # 3

# Round to specific decimal places
round(3.14159, 2)  # 3.14

Number Ranges

# Create number sequences
list(range(5))        # [0, 1, 2, 3, 4]
list(range(2, 6))     # [2, 3, 4, 5]
list(range(0, 10, 2)) # [0, 2, 4, 6, 8]

🔹 Text Functions

Convert to Text

# Turn anything into text
str(42)        # "42"
str(3.14)      # "3.14"
str(True)      # "True"

Check Text Content

# Check if text contains only numbers
"123".isdigit()    # True
"12a".isdigit()    # False

# Check if text contains only letters
"Hello".isalpha()  # True
"Hi123".isalpha()  # False

🔹 List Functions

Create Lists

# Make a list
list("abc")        # ['a', 'b', 'c']
list(range(3))     # [0, 1, 2]

Sort Lists

# Sort items
sorted([3, 1, 4])     # [1, 3, 4]
sorted(["c", "a"])    # ['a', 'c']

# Reverse order
reversed([1, 2, 3])   # [3, 2, 1]

Work with Items

# Check if item exists
"apple" in ["apple", "banana"]  # True

# Get all items with their position
list(enumerate(["a", "b"]))  # [(0, 'a'), (1, 'b')]

🔹 Type Conversion

Convert to Numbers

# Text to number
int("42")      # 42
float("3.14")  # 3.14

# Number to different type
int(3.9)       # 3 (removes decimal)
float(5)       # 5.0

Convert to True/False

# Check if something is true or false
bool(1)        # True
bool(0)        # False
bool("hi")     # True
bool("")       # False

🔹 File Functions

Open Files

# Read a file
with open("data.txt", "r") as file:
    content = file.read()
    print(content)

# Write to a file
with open("output.txt", "w") as file:
    file.write("Hello, file!")