Python-zero-to-hero/chapter5.html at main · bocaletto-luca/Python-zero-to-hero · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  <meta name="description"
        content="Chapter 5 of Python Zero to Hero: control flow with conditionals (if/elif/else), loops (for, while), break & continue." />
  <meta name="keywords"
        content="Python, control flow, if, elif, else, for, while, loops, break, continue" />
  <meta name="author" content="Luca Bocaletto" />
  <title>Chapter 5 – Control Flow | Python Zero to Hero</title>

  <!-- Bootstrap 5 CSS -->
  <link
    href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.1/dist/css/bootstrap.min.css"
    rel="stylesheet"
    integrity="sha384-YSa3P1QY0VSei3nHevwltF1Jxv2pT3z5z0R6x35o1XQdYzdgQc8sYC+bS9v+g3Tc"
    crossorigin="anonymous"
  />

  <!-- Highlight.js CSS -->
  <link
    rel="stylesheet"
    href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.8.0/styles/github.min.css"
    integrity="sha512-94jnYVzi0AuOmT1JrLJiqxGWM1ZwVz4i1oF6XD2fXZj2lq+OJ9GSeUWLeFN5svoe0WyWkDi/gAhFI8QeYQj1Rg=="
    crossorigin="anonymous"
    referrerpolicy="no-referrer"
  />

  <style>
    body { padding-top: 4.5rem; }
    pre code { font-size: .9rem; }
    .btn-py { font-family: monospace; }
  </style>
</head>
<body>
  <!-- Navbar -->
  <nav class="navbar navbar-expand-lg navbar-dark bg-dark fixed-top">
    <div class="container">
      <a class="navbar-brand" href="index.html">Python Zero to Hero</a>
      <button class="navbar-toggler" type="button" data-bs-toggle="collapse"
              data-bs-target="#navContent" aria-controls="navContent"
              aria-expanded="false" aria-label="Toggle navigation">
        <span class="navbar-toggler-icon"></span>
      </button>
      <div class="collapse navbar-collapse" id="navContent">
        <ul class="navbar-nav ms-auto">
          <li class="nav-item"><a class="nav-link" href="chapter4.html">Chapter 4</a></li>
          <li class="nav-item"><a class="nav-link" href="index.html">Index</a></li>
          <li class="nav-item"><a class="nav-link" href="chapter6.html">Chapter 6</a></li>
          <li class="nav-item">
            <a class="nav-link"
               href="https://github.com/bocaletto-luca/python-zero-to-hero"
               target="_blank">GitHub Repo</a>
          </li>
        </ul>
      </div>
    </div>
  </nav>

  <!-- Main Content -->
  <main class="container">
    <!-- Header -->
    <header class="my-4">
      <h1 class="display-6">Chapter 5: Control Flow</h1>
      <p class="text-muted">
        Direct the execution path of your programs using conditionals and loops.
      </p>
      <a href="src/chapter5.py" download class="btn btn-outline-primary btn-sm btn-py">
        Download <code>chapter5.py</code>
      </a>
      <hr>
    </header>

    <!-- Objectives -->
    <section id="objectives" class="mb-5">
      <h2>Objectives</h2>
      <ul>
        <li>Write <code>if</code>, <code>elif</code>, <code>else</code> branches.</li>
        <li>Create <code>for</code> loops over sequences and <code>range()</code>.</li>
        <li>Use <code>while</code> loops for repeated conditions.</li>
        <li>Control loops with <code>break</code> and <code>continue</code>.</li>
        <li>Understand nesting of conditionals and loops.</li>
      </ul>
    </section>

    <!-- 1. Conditional Statements -->
    <section id="conditionals" class="mb-5">
      <h2>1. Conditional Statements</h2>
      <p>Branch logic based on boolean expressions:</p>
      <pre><code class="python">x = 10
if x < 5:
    print("x is less than 5")
elif x < 15:
    print("x is between 5 and 14")
else:
    print("x is 15 or more")</code></pre>
      <p>You can nest conditions:</p>
      <pre><code class="python">score = 85
if score >= 90:
    grade = "A"
else:
    if score >= 80:
        grade = "B"
    else:
        grade = "C"
print(f"Grade: {grade}")</code></pre>
    </section>

    <!-- 2. for Loops -->
    <section id="for-loops" class="mb-5">
      <h2>2. for Loops</h2>
      <p>Iterate over sequences (lists, strings, ranges):</p>
      <pre><code class="python">fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print(fruit)

# using range()
for i in range(5):       # 0,1,2,3,4
    print(i)</code></pre>
      <p>You can also loop with index:</p>
      <pre><code class="python">for idx, val in enumerate(fruits, start=1):
    print(idx, val)</code></pre>
    </section>

    <!-- 3. while Loops -->
    <section id="while-loops" class="mb-5">
      <h2>3. while Loops</h2>
      <p>Repeat while a condition holds true:</p>
      <pre><code class="python">count = 0
while count < 3:
    print("Count is", count)
    count += 1</code></pre>
      <p>Use a sentinel or flag to control the loop:</p>
      <pre><code class="python">running = True
while running:
    cmd = input("Enter command (quit to exit): ")
    if cmd == "quit":
        running = False
    else:
        print("You typed:", cmd)</code></pre>
    </section>

    <!-- 4. break & continue -->
    <section id="break-continue" class="mb-5">
      <h2>4. break & continue</h2>
      <p>Alter loop execution flow:</p>
      <ul>
        <li><code>break</code>: exit loop immediately.</li>
        <li><code>continue</code>: skip to next iteration.</li>
      </ul>
      <pre><code class="python">for n in range(10):
    if n == 5:
        break        # stops loop at 5
    print(n)

for n in range(5):
    if n % 2 == 0:
        continue     # skip even numbers
    print(n)         # prints 1,3</code></pre>
    </section>

    <!-- Exercises -->
    <section id="exercises" class="mb-5">
      <h2>Exercises</h2>
      <ol>
        <li>Write a script that prints numbers 1–20, but stops at the first number divisible by 7.</li>
        <li>Ask the user for a password; keep prompting until they enter the correct one (<code>"secret"</code>).</li>
        <li>Loop through a list of names and print only those that start with a vowel using <code>continue</code>.</li>
        <li>Implement a nested loop to print a 5×5 multiplication table.</li>
      </ol>
    </section>

    <!-- Navigation -->
    <nav class="d-flex justify-content-between mb-5">
      <a href="chapter4.html" class="btn btn-outline-secondary">&larr; Chapter 4</a>
      <a href="chapter6.html" class="btn btn-primary">Chapter 6 &rarr;</a>
    </nav>
  </main>

  <!-- Footer -->
  <footer class="text-center py-4 border-top">
    <small>
      © 2025 Python Zero to Hero •
      <a href="https://github.com/bocaletto-luca/python-zero-to-hero" target="_blank">
        bocaletto-luca/python-zero-to-hero
      </a>
    </small>
  </footer>

  <!-- Bootstrap JS Bundle -->
  <script
    src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.1/dist/js/bootstrap.bundle.min.js"
    integrity="sha384-pQjTSprQoSWb8PQmxHkFvHUuI+13Z2VBxXc5xykxDc8/8aMbkwg/Sf5FCvbyT1Kg"
    crossorigin="anonymous"
  ></script>

  <!-- Highlight.js -->
  <script
    src="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.8.0/highlight.min.js"
    integrity="sha512-v+HDTvKi4ym72wvsLmDdWKH1Z9r7qmOZEk11Kd/PO5vQRO3KHSEt+XeajpxdsBUW5Fve4BJR+wHrHBW2ApwBMQ=="
    crossorigin="anonymous"
    referrerpolicy="no-referrer"
  ></script>
  <script>hljs.highlightAll();</script>
</body>
</html>