Input Output Tutorial

import math

name = "Alice"
age = 30
pi = math.pi

# F-strings (recommended) - Python 3.6+
message = f"Hello {name}, you are {age} years old"
precision = f"Pi is approximately {pi:.3f}"
calculation = f"2 + 2 = {2 + 2}"

# .format() method
message2 = "Hello {}, you are {} years old".format(name, age)
message3 = "Hello {name}, you are {age} years old".format(name=name, age=age)
indexed = "{0} and {1} and {0}".format("spam", "eggs")  # spam and eggs and spam

# Manual formatting
number = "42"
padded = number.rjust(10)      # Right-justify in 10 characters
centered = number.center(10)   # Center in 10 characters
zeros = number.zfill(5)        # Pad with zeros: 00042

# Format specifications
value = 1234.5678
print(f"{value:10.2f}")     # Right-align, 2 decimal places
print(f"{value:<10.2f}")    # Left-align
print(f"{value:^10.2f}")    # Center-align

# Different number formats
number = 42
print(f"Decimal: {number:d}")     # 42
print(f"Binary: {number:b}")      # 101010
print(f"Octal: {number:o}")       # 52
print(f"Hex: {number:x}")         # 2a
print(f"Hex upper: {number:X}")   # 2A

# Percentage and scientific notation
ratio = 0.875
print(f"Percentage: {ratio:.1%}")  # 87.5%
large = 1234567.89
print(f"Scientific: {large:.2e}") # 1.23e+06

# Writing to a file
with open('workfile.txt', 'w', encoding='utf-8') as f:
    f.write('This is a test\n')
    f.write('Hello, world!\n')

# Reading entire file
with open('workfile.txt', 'r', encoding='utf-8') as f:
    content = f.read()
    print(content)

# Reading line by line
with open('workfile.txt', 'r', encoding='utf-8') as f:
    for line in f:
        print(line.strip())  # Remove newline character

# Reading all lines into a list
with open('workfile.txt', 'r', encoding='utf-8') as f:
    lines = f.readlines()
    print(lines)

# Text modes
with open('file.txt', 'r') as f:    # Read
    pass
with open('file.txt', 'w') as f:    # Write (overwrites)
    pass
with open('file.txt', 'a') as f:    # Append
    pass

# Binary modes
with open('image.jpg', 'rb') as f:  # Read binary
    data = f.read()

with open('output.jpg', 'wb') as f: # Write binary
    f.write(data)

# Text mode with specific encoding
with open('unicode.txt', 'w', encoding='utf-8') as f:
    f.write('Hello, 世界! 🐍')

import json

# Python data structures
data = {
    'name': 'Alice',
    'age': 30,
    'languages': ['Python', 'JavaScript', 'Go'],
    'active': True,
    'balance': 123.45
}

# Convert to JSON string
json_string = json.dumps(data, indent=2)
print(json_string)

# Write JSON to file
with open('data.json', 'w', encoding='utf-8') as f:
    json.dump(data, f, indent=2)

# Read JSON from file
with open('data.json', 'r', encoding='utf-8') as f:
    loaded_data = json.load(f)
    print(loaded_data)

# Parse JSON string
parsed = json.loads(json_string)
print(parsed['name'])  # Alice

# Working with file positions
with open('workfile.txt', 'r+', encoding='utf-8') as f:
    f.write('Hello, world!')
    
    # Move to beginning
    f.seek(0)
    print(f.read())  # Read from beginning
    
    # Check current position
    print(f"Position: {f.tell()}")
    
    # Move to specific position
    f.seek(7)  # Move to 7th character
    f.write('Python!')

try:
    with open('nonexistent.txt', 'r') as f:
        content = f.read()
except FileNotFoundError:
    print("File not found!")
except PermissionError:
    print("Permission denied!")
except IOError as e:
    print(f"I/O error: {e}")

# Check if file exists before opening
import os
filename = 'data.txt'
if os.path.exists(filename):
    with open(filename, 'r') as f:
        print(f.read())
else:
    print("File doesn't exist")

# Count lines, words, and characters
def analyze_file(filename):
    try:
        with open(filename, 'r', encoding='utf-8') as f:
            lines = f.readlines()
            
        line_count = len(lines)
        word_count = sum(len(line.split()) for line in lines)
        char_count = sum(len(line) for line in lines)
        
        return {
            'lines': line_count,
            'words': word_count,
            'characters': char_count
        }
    except FileNotFoundError:
        return None

# Usage
stats = analyze_file('example.txt')
if stats:
    print(f"Lines: {stats['lines']}")
    print(f"Words: {stats['words']}")
    print(f"Characters: {stats['characters']}")

import csv

# Write CSV
data = [
    ['Name', 'Age', 'City'],
    ['Alice', '30', 'New York'],
    ['Bob', '25', 'Los Angeles'],
    ['Charlie', '35', 'Chicago']
]

with open('people.csv', 'w', newline='', encoding='utf-8') as f:
    writer = csv.writer(f)
    writer.writerows(data)

# Read CSV
with open('people.csv', 'r', encoding='utf-8') as f:
    reader = csv.reader(f)
    for row in reader:
        print(row)

# CSV with DictReader/DictWriter
with open('people.csv', 'r', encoding='utf-8') as f:
    reader = csv.DictReader(f)
    for row in reader:
        print(f"{row['Name']} is {row['Age']} years old")

import configparser

# Create config
config = configparser.ConfigParser()
config['DEFAULT'] = {
    'ServerAliveInterval': '45',
    'Compression': 'yes'
}
config['database'] = {
    'host': 'localhost',
    'port': '5432',
    'name': 'myapp'
}

# Write config file
with open('config.ini', 'w') as f:
    config.write(f)

# Read config file
config = configparser.ConfigParser()
config.read('config.ini')

print(config['database']['host'])  # localhost
print(config.getint('database', 'port'))  # 5432 (as integer)