156156 div.columns{display: flex; gap: min(4vw, 1.5em);}
157157 div.column{flex: auto; overflow-x: auto;}
158158 div.hanging-indent{margin-left: 1.5em; text-indent: -1.5em;}
159- ul.task-list{list-style: none;}
159+ /* The extra [class] is a hack that increases specificity enough to
160+ override a similar rule in reveal.js */
161+ ul.task-list[class]{list-style: none;}
160162 ul.task-list li input[type="checkbox"] {
163+ font-size: inherit;
161164 width: 0.8em;
162165 margin: 0 0.8em 0.2em -1.6em;
163166 vertical-align: middle;
@@ -506,55 +509,36 @@ class="uri">https://docs.python.org/library/stdtypes.html#string-methods</a></p>
506509<p><a
507510href="https://docs.python.org/library/stdtypes.html#string-methods"
508511class="uri">https://docs.python.org/library/stdtypes.html#string-methods</a>.</p>
509- <h2 id="format-operator">Format operator</h2>
510- <p> </p>
511- <p>The <em>format operator</em>, <code>%</code> allows us to construct
512- strings, replacing parts of the strings with the data stored in
513- variables. When applied to integers, <code>%</code> is the modulus
514- operator. But when the first operand is a string, <code>%</code> is the
515- format operator.</p>
516- <p></p>
517- <p>The first operand is the <em>format string</em>, which contains one
518- or more <em>format sequences</em> that specify how the second operand is
519- formatted. The result is a string.</p>
512+ <h2 id="formatted-string-literals">Formatted String Literals</h2>
520513<p></p>
521- <p>For example, the format sequence <code>%d</code> means that the
522- second operand should be formatted as an integer (“d” stands for
523- “decimal”):</p>
514+ <p>A formatted string literal (often referred to simply as an f-string)
515+ allows Python expressions to be used within string literals. This is
516+ accomplished by prepending an <code>f</code> to the string literal and
517+ enclosing expressions in curly braces <code>{}</code>.</p>
518+ <p>For example, wrapping a variable name in curly braces inside an
519+ f-string will cause it to be replaced by its value:</p>
524520<pre class="python"><code>>>> camels = 42
525- >>> '%d ' % camels
521+ >>> f '{camels} '
526522'42'</code></pre>
527523<p>The result is the string ‘42’, which is not to be confused with the
528524integer value 42.</p>
529- <p>A format sequence can appear anywhere in the string, so you can embed
530- a value in a sentence:</p>
525+ <p>An expression can appear anywhere in the string, so you can embed a
526+ value in a sentence:</p>
531527<pre class="python"><code>>>> camels = 42
532- >>> 'I have spotted %d camels.' % camels
528+ >>> f 'I have spotted {camels} camels.'
533529'I have spotted 42 camels.'</code></pre>
534- <p>If there is more than one format sequence in the string, the second
535- argument has to be a tuple<a href="#fn1" class="footnote-ref"
536- id="fnref1" role="doc-noteref"><sup>1</sup></a>. Each format sequence is
537- matched with an element of the tuple, in order.</p>
538- <p>The following example uses <code>%d</code> to format an integer,
539- <code>%g</code> to format a floating-point number (don’t ask why), and
540- <code>%s</code> to format a string:</p>
541- <pre class="python"><code>>>> 'In %d years I have spotted %g %s.' % (3, 0.1, 'camels')
530+ <p>Several expressions can be included within a single string literal in
531+ order to create more complex strings.</p>
532+ <pre class="python"><code>>>> years = 3
533+ >>> count = .1
534+ >>> species = 'camels'
535+ >>> f'In {years} years I have spotted {count} {species}.'
542536'In 3 years I have spotted 0.1 camels.'</code></pre>
543- <p>The number of elements in the tuple must match the number of format
544- sequences in the string. The types of the elements also must match the
545- format sequences:</p>
546- <p> </p>
547- <pre class="python"><code>>>> '%d %d %d' % (1, 2)
548- TypeError: not enough arguments for format string
549- >>> '%d' % 'dollars'
550- TypeError: %d format: a number is required, not str</code></pre>
551- <p>In the first example, there aren’t enough elements; in the second,
552- the element is the wrong type.</p>
553- <p>The format operator is powerful, but it can be difficult to use. You
554- can read more about it at</p>
537+ <p>Formatted string literals are powerful, and they can do even more
538+ than is covered here. You can read more about them at</p>
555539<p><a
556- href="https://docs.python.org/library/stdtypes .html#printf-style- string-formatting "
557- class="uri">https://docs.python.org/library/stdtypes .html#printf-style- string-formatting </a>.</p>
540+ href="https://docs.python.org/3/tutorial/inputoutput .html#formatted- string-literals "
541+ class="uri">https://docs.python.org/3/tutorial/inputoutput .html#formatted- string-literals </a>.</p>
558542<h2 id="debugging">Debugging</h2>
559543<p></p>
560544<p>A skill that you should cultivate as you program is always asking
@@ -684,7 +668,7 @@ class="uri">https://docs.python.org/library/stdtypes.html#printf-style-string-fo
684668<p> </p>
685669<p><strong>Exercise 6: Read the documentation of the string methods at
686670<a href="https://docs.python.org/library/stdtypes.html#string-methods"
687- class="uri">https://docs.python.org/library/stdtypes.html#string-methods</a>
671+ class="uri">https://docs.python.org/library/stdtypes.html#string-methods</a>.
688672You might want to experiment with some of them to make sure you
689673understand how they work. <code>strip</code> and <code>replace</code>
690674are particularly useful.</strong></p>
@@ -693,15 +677,6 @@ class="uri">https://docs.python.org/library/stdtypes.html#string-methods</a>
693677indicate optional arguments. So <code>sub</code> is required, but
694678<code>start</code> is optional, and if you include <code>start</code>,
695679then <code>end</code> is optional.</strong></p>
696- <aside id="footnotes" class="footnotes footnotes-end-of-document"
697- role="doc-endnotes">
698- <hr />
699- <ol>
700- <li id="fn1"><p>A tuple is a sequence of comma-separated values inside a
701- pair of parenthesis. We will cover tuples in Chapter 10<a href="#fnref1"
702- class="footnote-back" role="doc-backlink">↩︎</a></p></li>
703- </ol>
704- </aside>
705680</body>
706681</html>
707682<?php if ( file_exists ("../bookfoot.php " ) ) {
0 commit comments