# Basic file reading
with open('example.txt', 'r') as file:
    content = file.read()
    print(content)

# Read entire file at once
filename = 'sample.txt'

# Read method - gets all content as string
with open(filename, 'r') as file:
    content = file.read()
    print(f"Entire file: {content[:50]}...")

# Readlines method - gets all lines as list
with open(filename, 'r') as file:
    lines = file.readlines()
    print(f"Number of lines: {len(lines)}")
    if lines:
        print(f"First line: {lines[0].strip()}")

print("File reading completed")

# Memory efficient line-by-line reading
with open(filename, 'r') as file:
    for line_num, line in enumerate(file, 1):
        print(f"Line {line_num}: {line.strip()}")
        if line_num >= 3:  # Show first 3 lines only
            break

print("Line-by-line reading completed")

# Read one line at a time
with open(filename, 'r') as file:
    first_line = file.readline()
    second_line = file.readline()
    print(f"First: {first_line.strip()}")
    print(f"Second: {second_line.strip()}")

print("Single line reading completed")

import os

# Check if file exists before reading
filename = 'config.txt'
if os.path.exists(filename):
    with open(filename, 'r') as file:
        content = file.read()
        print(f"File content: {content}")
else:
    print("File not found")

print("File existence check completed")

# Reading with encoding specification and error handling
try:
    with open(filename, 'r', encoding='utf-8') as file:
        content = file.read()
        print(f"UTF-8 content: {content}")
except FileNotFoundError:
    print("File not found")
except UnicodeDecodeError:
    print("Encoding error")

print("Encoding-specific reading completed")

# Reading specific number of characters
try:
    with open(filename, 'r') as file:
        chunk = file.read(100)  # Read first 100 characters
        print(f"First 100 chars: {chunk}")
except FileNotFoundError:
    print("File not found")

# Skip empty lines and comments
def read_config_file(filename):
    config_lines = []
    try:
        with open(filename, 'r') as file:
            for line in file:
                line = line.strip()
                if line and not line.startswith('#'):
                    config_lines.append(line)
        return config_lines
    except FileNotFoundError:
        return []

config = read_config_file('config.txt')
print(f"Config lines: {config}")