Practice Questions — File Handling in Python

# Create the file
with open("sample.txt", "w") as f:
    f.write("Python is amazing\n")
    f.write("File handling is useful\n")
    f.write("Practice makes perfect\n")
    f.write("Keep coding daily\n")
    f.write("Learn something new\n")

# Count lines, words, characters
lines = 0
words = 0
chars = 0

with open("sample.txt", "r") as f:
    for line in f:
        lines += 1
        words += len(line.split())
        chars += len(line.strip())

print(f"Lines: {lines}")
print(f"Words: {words}")
print(f"Characters: {chars}")

# Write student data
students = [("Aarav", 92), ("Priya", 97), ("Rohan", 78), ("Meera", 85), ("Vikram", 70)]

with open("marks.csv", "w") as f:
    f.write("Name,Marks\n")
    for name, marks in students:
        f.write(f"{name},{marks}\n")

# Read and analyze
topper_name = ""
topper_marks = 0
total = 0
count = 0

with open("marks.csv", "r") as f:
    f.readline()  # Skip header
    for line in f:
        name, marks = line.strip().split(",")
        marks = int(marks)
        total += marks
        count += 1
        if marks > topper_marks:
            topper_marks = marks
            topper_name = name

print(f"Topper: {topper_name} with {topper_marks} marks")
print(f"Class average: {total / count}")

def log_message(filename, message):
    # Count existing lines
    try:
        with open(filename, "r") as f:
            count = sum(1 for _ in f)
    except FileNotFoundError:
        count = 0
    
    with open(filename, "a") as f:
        f.write(f"[{count + 1}] {message}\n")

# Clear and write fresh log
with open("app.log", "w") as f:
    pass  # Clear the file

log_message("app.log", "System started")
log_message("app.log", "Loading data")
log_message("app.log", "Processing records")
log_message("app.log", "Saving results")
log_message("app.log", "System shutdown")

# Display log
with open("app.log", "r") as f:
    print(f.read().strip())

def find_replace(filename, old_text, new_text):
    with open(filename, "r") as f:
        content = f.read()
    
    count = content.count(old_text)
    new_content = content.replace(old_text, new_text)
    
    with open(filename, "w") as f:
        f.write(new_content)
    
    return count

# Create test file
with open("test.txt", "w") as f:
    f.write("Python is great. Python is popular.\n")

with open("test.txt", "r") as f:
    print(f"Before: {f.read().strip()}")

count = find_replace("test.txt", "Python", "Python3")

with open("test.txt", "r") as f:
    print(f"After: {f.read().strip()}")
print(f"Replacements made: {count}")

import os

def merge_files(file_list, output_file):
    with open(output_file, "w") as out:
        for filename in file_list:
            if not os.path.exists(filename):
                print(f"Warning: {filename} not found, skipping.")
                continue
            out.write(f"--- {filename} ---\n")
            with open(filename, "r") as f:
                out.write(f.read())
            if not out.tell():  # ensure newline between files
                out.write("\n")

# Create test files
for i in range(1, 4):
    with open(f"part{i}.txt", "w") as f:
        f.write(f"Hello from file {i}\n")

merge_files(["part1.txt", "part2.txt", "part3.txt"], "merged.txt")

with open("merged.txt", "r") as f:
    print(f.read().strip())

def add_line_numbers(input_file, output_file):
    count = 0
    with open(input_file, "r") as src:
        with open(output_file, "w") as dst:
            for num, line in enumerate(src, 1):
                dst.write(f"{num}: {line}")
                count = num
    return count

# Create test file
with open("input.txt", "w") as f:
    f.write("Python is versatile\n")
    f.write("It supports file handling\n")
    f.write("Practice daily\n")

total = add_line_numbers("input.txt", "numbered.txt")

with open("numbered.txt", "r") as f:
    print(f.read().strip())
print(f"Total lines: {total}")

def word_frequency(filename):
    freq = {}
    with open(filename, "r") as f:
        for line in f:
            # Remove punctuation and lowercase
            for char in ".,!?;:":
                line = line.replace(char, "")
            for word in line.lower().split():
                freq[word] = freq.get(word, 0) + 1
    return freq

# Create test file
with open("article.txt", "w") as f:
    f.write("The Python language is great. Python is used for the web.\n")
    f.write("The community is strong and the resources are vast.\n")
    f.write("Learning Python and practicing is essential for growth.\n")

freq = word_frequency("article.txt")
sorted_words = sorted(freq.items(), key=lambda x: x[1], reverse=True)

print("Top 5 words:")
for word, count in sorted_words[:5]:
    print(f"  {word}: {count}")

def read_config(filename):
    config = {}
    with open(filename, "r") as f:
        for line in f:
            line = line.strip()
            if not line or line.startswith("#"):
                continue
            if "=" in line:
                key, value = line.split("=", 1)
                config[key.strip()] = value.strip()
    return config

def write_config(filename, config):
    with open(filename, "w") as f:
        f.write("# Configuration File\n\n")
        for key, value in config.items():
            f.write(f"{key} = {value}\n")

# Create config file
with open("app.conf", "w") as f:
    f.write("# Server settings\n")
    f.write("host = localhost\n")
    f.write("port = 8080\n")
    f.write("\n")
    f.write("# App settings\n")
    f.write("debug = true\n")
    f.write("name = MyApp\n")

config = read_config("app.conf")
print(config)

config["port"] = "9090"
write_config("app_updated.conf", config)
print("Config saved successfully.")