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  <meta name="description"
        content="Chapter 8 of Python Zero to Hero: file input/output in console—read/write text, CSV and binary files using context managers."/>
  <meta name="keywords"
        content="Python, file I/O, open, read, write, CSV, binary, with, context manager"/>
  <meta name="author" content="Luca Bocaletto"/>
  <title>Chapter 8 – File I/O | Python Zero to Hero</title>

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    <header class="my-4">
      <h1 class="display-6">Chapter 8: File I/O</h1>
      <p class="text-muted">
        Learn to read and write text, CSV, and binary files from the console using Python.
      </p>
      <a href="src/chapter8.py" download class="btn btn-outline-primary btn-sm btn-py">
        Download <code>chapter8.py</code>
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    <!-- Objectives -->
    <section id="objectives" class="mb-5">
      <h2>Objectives</h2>
      <ul>
        <li>Open files in text and binary modes for reading and writing.</li>
        <li>Read entire file, line by line, or in chunks.</li>
        <li>Write text and binary data, use <code>writelines()</code>.</li>
        <li>Use the <code>csv</code> module to parse and generate CSV files.</li>
        <li>Manage files safely with context managers (<code>with</code> statement).</li>
      </ul>
    </section>

    <!-- 1. Text File Reading -->
    <section id="read-text" class="mb-5">
      <h2>1. Reading Text Files</h2>
      <p>Open in read mode (<code>'r'</code>), then:</p>
      <pre><code class="python">with open("data.txt", "r", encoding="utf-8") as f:
    content = f.read()         # entire file as one string
    lines   = f.readlines()    # list of lines
    f.seek(0)                  # go back to start
    for line in f:             # iterate line by line
        print(line.strip())</code></pre>
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    <!-- 2. Text File Writing -->
    <section id="write-text" class="mb-5">
      <h2>2. Writing Text Files</h2>
      <p>Open in write (<code>'w'</code>) or append (<code>'a'</code>) mode:</p>
      <pre><code class="python">lines = ["First line\n", "Second line\n"]
with open("output.txt", "w", encoding="utf-8") as f:
    f.write("Header\n")
    f.writelines(lines)      # write multiple lines at once</code></pre>
    <p>Modes:</p>
      <table class="table table-sm table-bordered io-table">
        <thead>
          <tr><th>Mode</th><th>Meaning</th></tr>
        </thead>
        <tbody>
          <tr><td><code>'r'</code></td><td>Read (default), file must exist</td></tr>
          <tr><td><code>'w'</code></td><td>Write, truncate or create</td></tr>
          <tr><td><code>'a'</code></td><td>Append, create if not exists</td></tr>
          <tr><td><code>'r+'</code></td><td>Read/write</td></tr>
          <tr><td><code>'b'</code> suffix</td><td>Binary mode</td></tr>
        </tbody>
      </table>
    </section>

    <!-- 3. CSV File Handling -->
    <section id="csv" class="mb-5">
      <h2>3. CSV File Handling</h2>
      <p>Use the built-in <code>csv</code> module:</p>
      <h3>a) Reading CSV</h3>
      <pre><code class="python">import csv

with open("records.csv", newline="", encoding="utf-8") as csvfile:
    reader = csv.reader(csvfile)
    for row in reader:
        print(row)           # each row is a list of strings</code></pre>
      <h3>b) Writing CSV</h3>
      <pre><code class="python">import csv

rows = [["Name","Age"], ["Alice","30"], ["Bob","25"]]
with open("out.csv", "w", newline="", encoding="utf-8") as csvfile:
    writer = csv.writer(csvfile)
    writer.writerows(rows)</code></pre>
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    <!-- 4. Binary File I/O -->
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      <h2>4. Binary File I/O</h2>
      <p>Open in binary mode (<code>'rb'</code>, <code>'wb'</code>):</p>
      <pre><code class="python"># Read image bytes
with open("image.png", "rb") as fin:
    data = fin.read()

# Write bytes to new file
with open("copy.png", "wb") as fout:
    fout.write(data)</code></pre>
    </section>

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      <h2>Exercises</h2>
      <ol>
        <li>Create a text file with ten lines, then write a script to count and print the number of lines.</li>
        <li>Build a CSV file of products (name, price), then read it and calculate the total cost.</li>
        <li>Write a function to append a log entry with timestamp to a log file.</li>
        <li>Copy a binary file (e.g., an image) from source to destination using chunks.</li>
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