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<!DOCTYPE html>
<html lang="en">
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<title>Go sort Package — Ultimate Guide</title>
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</head>
<body>
<div class="hero">
<h1>Go <span>sort</span> Package</h1>
<p>Sort slices with a one-liner, implement custom orderings, keep equal elements stable, and binary-search sorted data.</p>
<div class="hero-pills">
<span>sort.Slice</span>
<span>sort.SliceStable</span>
<span>sort.Ints / Strings</span>
<span>sort.Interface</span>
<span>sort.Search</span>
<span>sort.IsSorted</span>
<span>Reverse</span>
</div>
</div>
<div class="layout">
<nav class="pkg-nav">
<a href="index.html" class="home-link">Go Handbook</a>
<div class="nav-group">Language</div>
<ul class="pkg-list">
<li><a href="basics.html"><span class="pkg-icon">📖</span>Basics</a></li>
<li><a href="data-structures.html"><span class="pkg-icon">📦</span>Data Structures</a></li>
<li><a href="concurrency.html"><span class="pkg-icon">🔀</span>Concurrency</a></li>
<li><a href="testing.html"><span class="pkg-icon">🧪</span>Testing</a></li>
<li><a href="reflection.html"><span class="pkg-icon">🔬</span>Reflection</a></li>
<li><a href="file-data.html"><span class="pkg-icon">📁</span>File & Data</a></li>
<li><a href="web.html"><span class="pkg-icon">🌐</span>Web</a></li>
<li><a href="packages-modules.html"><span class="pkg-icon">🗃</span>Packages & Modules</a></li>
<li><a href="performance.html"><span class="pkg-icon">⚡</span>Performance</a></li>
<li><a href="gotchas.html"><span class="pkg-icon">⚠️</span>Gotchas</a></li>
</ul>
<div class="nav-group">Packages</div>
<ul class="pkg-list">
<li><a href="strings-package-guide.html"><span class="pkg-icon">🔤</span>strings</a></li>
<li><a href="fmt-package-guide.html"><span class="pkg-icon">🖨</span>fmt</a></li>
<li><a href="strconv-package-guide.html"><span class="pkg-icon">🔢</span>strconv</a></li>
<li><a href="sort-package-guide.html" class="active"><span class="pkg-icon">📊</span>sort</a></li>
<li><a href="slices-package-guide.html"><span class="pkg-icon">🗂</span>slices</a></li>
<li><a href="io-package-guide.html"><span class="pkg-icon">🔌</span>io</a></li>
<li><a href="os-package-guide.html"><span class="pkg-icon">💻</span>os</a></li>
<li><a href="errors-package-guide.html"><span class="pkg-icon">⚠️</span>errors</a></li>
<li><a href="context-package-guide.html"><span class="pkg-icon">🎯</span>context</a></li>
<li><a href="time-package-guide.html"><span class="pkg-icon">⏱</span>time</a></li>
<li><a href="math-package-guide.html"><span class="pkg-icon">🧮</span>math</a></li>
</ul>
</nav>
<main class="content">
<!-- ── 1. SLICE HELPERS ──────────────────────────────── -->
<section class="section" id="slice">
<div class="section-header">
<div class="section-icon icon-blue">⚡</div>
<h2>Sorting Slices</h2>
<span class="section-tag">sort.Slice · sort.SliceStable</span>
</div>
<div class="callout">
<span class="callout-icon">ℹ️</span>
<div><code>sort.Slice</code> is the everyday workhorse. Pass the slice and a <em>less</em> function that returns true when element <code>i</code> should come before element <code>j</code>. It uses an unstable sort — equal elements may be reordered.</div>
</div>
<div class="card">
<div class="card-header">
<span class="card-title">sort.Slice — sort any slice with a comparator</span>
<span class="card-badge badge-blue">sort.Slice</span>
</div>
<div class="code-wrap">
<pre>nums := []<span class="typ">int</span>{<span class="num">5</span>, <span class="num">2</span>, <span class="num">8</span>, <span class="num">1</span>, <span class="num">9</span>, <span class="num">3</span>}
<span class="pkg">sort</span>.<span class="fn">Slice</span>(nums, <span class="kw">func</span>(i, j <span class="typ">int</span>) <span class="typ">bool</span> {
<span class="kw">return</span> nums[i] < nums[j] <span class="cmt">// ascending</span>
})
<span class="cmt">// [1 2 3 5 8 9]</span>
<span class="cmt">// Descending — flip the comparison</span>
<span class="pkg">sort</span>.<span class="fn">Slice</span>(nums, <span class="kw">func</span>(i, j <span class="typ">int</span>) <span class="typ">bool</span> {
<span class="kw">return</span> nums[i] > nums[j]
})
<span class="cmt">// [9 8 5 3 2 1]</span>
words := []<span class="typ">string</span>{<span class="str">"banana"</span>, <span class="str">"apple"</span>, <span class="str">"cherry"</span>}
<span class="pkg">sort</span>.<span class="fn">Slice</span>(words, <span class="kw">func</span>(i, j <span class="typ">int</span>) <span class="typ">bool</span> {
<span class="kw">return</span> words[i] < words[j]
})
<span class="cmt">// [apple banana cherry]</span></pre>
</div>
</div>
<div class="card">
<div class="card-header">
<span class="card-title">Sorting structs by a field</span>
<span class="card-badge badge-blue">Structs</span>
</div>
<div class="code-wrap">
<pre><span class="kw">type</span> <span class="typ">Person</span> <span class="kw">struct</span> {
Name string
Age <span class="typ">int</span>
}
people := []<span class="typ">Person</span>{
{<span class="str">"Alice"</span>, <span class="num">30</span>},
{<span class="str">"Bob"</span>, <span class="num">25</span>},
{<span class="str">"Charlie"</span>, <span class="num">35</span>},
{<span class="str">"Diana"</span>, <span class="num">25</span>},
}
<span class="cmt">// Sort by Age ascending</span>
<span class="pkg">sort</span>.<span class="fn">Slice</span>(people, <span class="kw">func</span>(i, j <span class="typ">int</span>) <span class="typ">bool</span> {
<span class="kw">return</span> people[i].Age < people[j].Age
})
<span class="cmt">// [{Bob 25} {Diana 25} {Alice 30} {Charlie 35}]</span>
<span class="cmt">// (Bob and Diana order is not guaranteed — use SliceStable for that)</span>
<span class="cmt">// Sort by Name alphabetically</span>
<span class="pkg">sort</span>.<span class="fn">Slice</span>(people, <span class="kw">func</span>(i, j <span class="typ">int</span>) <span class="typ">bool</span> {
<span class="kw">return</span> people[i].Name < people[j].Name
})
<span class="cmt">// [{Alice 30} {Bob 25} {Charlie 35} {Diana 25}]</span></pre>
</div>
</div>
<div class="card">
<div class="card-header">
<span class="card-title">sort.SliceStable — preserve order of equal elements</span>
<span class="card-badge badge-green">Stable</span>
</div>
<div class="code-wrap">
<pre><span class="cmt">// SliceStable guarantees that equal elements keep their original relative order</span>
<span class="cmt">// Useful when sorting by one field but preserving a prior sort on another</span>
<span class="cmt">// Step 1: sort by Name</span>
<span class="pkg">sort</span>.<span class="fn">SliceStable</span>(people, <span class="kw">func</span>(i, j <span class="typ">int</span>) <span class="typ">bool</span> {
<span class="kw">return</span> people[i].Name < people[j].Name
})
<span class="cmt">// Step 2: sort by Age — Name order is preserved within equal ages</span>
<span class="pkg">sort</span>.<span class="fn">SliceStable</span>(people, <span class="kw">func</span>(i, j <span class="typ">int</span>) <span class="typ">bool</span> {
<span class="kw">return</span> people[i].Age < people[j].Age
})
<span class="cmt">// [{Bob 25} {Diana 25} {Alice 30} {Charlie 35}]</span>
<span class="cmt">// Bob comes before Diana (alphabetical) because SliceStable preserved it</span></pre>
</div>
</div>
</section>
<!-- ── 2. BUILT-IN CONVENIENCE ───────────────────────── -->
<section class="section" id="builtins">
<div class="section-header">
<div class="section-icon icon-green">🎯</div>
<h2>Built-in Convenience Functions</h2>
<span class="section-tag">Ints · Strings · Float64s</span>
</div>
<div class="callout tip">
<span class="callout-icon">💡</span>
<div>For the three most common types there are pre-built functions so you don't need to write a comparator. Each also has a corresponding <code>AreSorted</code> check and <code>Search</code> variant.</div>
</div>
<div class="two-col">
<div class="card">
<div class="card-header">
<span class="card-title">sort.Ints & sort.Strings</span>
<span class="card-badge badge-green">Convenience</span>
</div>
<div class="code-wrap">
<pre>nums := []<span class="typ">int</span>{<span class="num">3</span>, <span class="num">1</span>, <span class="num">4</span>, <span class="num">1</span>, <span class="num">5</span>, <span class="num">9</span>}
<span class="pkg">sort</span>.<span class="fn">Ints</span>(nums)
<span class="cmt">// [1 1 3 4 5 9]</span>
words := []<span class="typ">string</span>{<span class="str">"go"</span>, <span class="str">"rust"</span>, <span class="str">"c"</span>}
<span class="pkg">sort</span>.<span class="fn">Strings</span>(words)
<span class="cmt">// [c go rust]</span>
floats := []<span class="typ">float64</span>{<span class="num">3.14</span>, <span class="num">1.41</span>, <span class="num">2.71</span>}
<span class="pkg">sort</span>.<span class="fn">Float64s</span>(floats)
<span class="cmt">// [1.41 2.71 3.14]</span></pre>
</div>
</div>
<div class="card">
<div class="card-header">
<span class="card-title">IntsAreSorted & StringsAreSorted</span>
<span class="card-badge badge-green">Check</span>
</div>
<div class="code-wrap">
<pre>nums := []<span class="typ">int</span>{<span class="num">1</span>, <span class="num">2</span>, <span class="num">3</span>, <span class="num">5</span>}
<span class="pkg">sort</span>.<span class="fn">IntsAreSorted</span>(nums) <span class="cmt">// true</span>
unsorted := []<span class="typ">int</span>{<span class="num">3</span>, <span class="num">1</span>, <span class="num">2</span>}
<span class="pkg">sort</span>.<span class="fn">IntsAreSorted</span>(unsorted) <span class="cmt">// false</span>
words := []<span class="typ">string</span>{<span class="str">"a"</span>, <span class="str">"b"</span>, <span class="str">"c"</span>}
<span class="pkg">sort</span>.<span class="fn">StringsAreSorted</span>(words) <span class="cmt">// true</span>
<span class="cmt">// Generic version — works with any less function</span>
<span class="pkg">sort</span>.<span class="fn">SliceIsSorted</span>(nums, <span class="kw">func</span>(i, j <span class="typ">int</span>) <span class="typ">bool</span> {
<span class="kw">return</span> nums[i] < nums[j]
}) <span class="cmt">// true</span></pre>
</div>
</div>
</div>
</section>
<!-- ── 3. MULTI-KEY SORT ─────────────────────────────── -->
<section class="section" id="multikey">
<div class="section-header">
<div class="section-icon icon-gold">🔑</div>
<h2>Multi-Key Sorting</h2>
<span class="section-tag">Primary · Secondary · Tiebreak</span>
</div>
<div class="card">
<div class="card-header">
<span class="card-title">Sorting by multiple fields in one pass</span>
<span class="card-badge badge-gold">Multi-Key</span>
</div>
<div class="code-wrap">
<pre><span class="kw">type</span> <span class="typ">Employee</span> <span class="kw">struct</span> {
Dept <span class="typ">string</span>
Name <span class="typ">string</span>
Salary <span class="typ">int</span>
}
employees := []<span class="typ">Employee</span>{
{<span class="str">"Eng"</span>, <span class="str">"Zara"</span>, <span class="num">90000</span>},
{<span class="str">"Eng"</span>, <span class="str">"Alice"</span>, <span class="num">95000</span>},
{<span class="str">"HR"</span>, <span class="str">"Bob"</span>, <span class="num">70000</span>},
{<span class="str">"Eng"</span>, <span class="str">"Alice"</span>, <span class="num">88000</span>},
}
<span class="cmt">// Primary: Dept asc Secondary: Name asc Tertiary: Salary desc</span>
<span class="pkg">sort</span>.<span class="fn">Slice</span>(employees, <span class="kw">func</span>(i, j <span class="typ">int</span>) <span class="typ">bool</span> {
a, b := employees[i], employees[j]
<span class="kw">if</span> a.Dept != b.Dept {
<span class="kw">return</span> a.Dept < b.Dept
}
<span class="kw">if</span> a.Name != b.Name {
<span class="kw">return</span> a.Name < b.Name
}
<span class="kw">return</span> a.Salary > b.Salary <span class="cmt">// highest salary first within same name</span>
})
<span class="cmt">// [{Eng Alice 95000} {Eng Alice 88000} {Eng Zara 90000} {HR Bob 70000}]</span></pre>
</div>
</div>
</section>
<!-- ── 4. SORT.INTERFACE ─────────────────────────────── -->
<section class="section" id="interface">
<div class="section-header">
<div class="section-icon icon-purple">🎭</div>
<h2>sort.Interface</h2>
<span class="section-tag">Len · Less · Swap</span>
</div>
<div class="callout">
<span class="callout-icon">ℹ️</span>
<div>Implement <code>sort.Interface</code> on your own type to use <code>sort.Sort</code>, <code>sort.Stable</code>, and <code>sort.Reverse</code>. This is the older, more verbose approach — prefer <code>sort.Slice</code> for simple cases.</div>
</div>
<div class="card">
<div class="card-header">
<span class="card-title">Implementing sort.Interface</span>
<span class="card-badge badge-purple">Interface</span>
</div>
<div class="code-wrap">
<pre><span class="kw">type</span> <span class="typ">ByLength</span> []<span class="typ">string</span>
<span class="kw">func</span> (b <span class="typ">ByLength</span>) <span class="fn">Len</span>() <span class="typ">int</span> { <span class="kw">return</span> <span class="fn">len</span>(b) }
<span class="kw">func</span> (b <span class="typ">ByLength</span>) <span class="fn">Swap</span>(i, j <span class="typ">int</span>) { b[i], b[j] = b[j], b[i] }
<span class="kw">func</span> (b <span class="typ">ByLength</span>) <span class="fn">Less</span>(i, j <span class="typ">int</span>) <span class="typ">bool</span> { <span class="kw">return</span> <span class="fn">len</span>(b[i]) < <span class="fn">len</span>(b[j]) }
words := <span class="typ">ByLength</span>{<span class="str">"peach"</span>, <span class="str">"kiwi"</span>, <span class="str">"pineapple"</span>, <span class="str">"fig"</span>}
<span class="pkg">sort</span>.<span class="fn">Sort</span>(words)
<span class="cmt">// [fig kiwi peach pineapple]</span>
<span class="cmt">// Stable version — preserves original order for equal lengths</span>
<span class="pkg">sort</span>.<span class="fn">Stable</span>(words)</pre>
</div>
</div>
<div class="card">
<div class="card-header">
<span class="card-title">sort.Reverse — wrap any Interface to flip the order</span>
<span class="card-badge badge-purple">Reverse</span>
</div>
<div class="code-wrap">
<pre><span class="cmt">// sort.Reverse wraps any sort.Interface to sort in reverse</span>
words := <span class="typ">ByLength</span>{<span class="str">"peach"</span>, <span class="str">"kiwi"</span>, <span class="str">"pineapple"</span>, <span class="str">"fig"</span>}
<span class="pkg">sort</span>.<span class="fn">Sort</span>(<span class="pkg">sort</span>.<span class="fn">Reverse</span>(words))
<span class="cmt">// [pineapple peach kiwi fig]</span>
<span class="cmt">// Also works with the convenience types</span>
nums := <span class="pkg">sort</span>.<span class="fn">IntSlice</span>{<span class="num">3</span>, <span class="num">1</span>, <span class="num">4</span>, <span class="num">1</span>, <span class="num">5</span>}
<span class="pkg">sort</span>.<span class="fn">Sort</span>(<span class="pkg">sort</span>.<span class="fn">Reverse</span>(nums))
<span class="cmt">// [5 4 3 1 1]</span>
<span class="cmt">// For sort.Slice, just flip the less function instead</span>
<span class="pkg">sort</span>.<span class="fn">Slice</span>(nums, <span class="kw">func</span>(i, j <span class="typ">int</span>) <span class="typ">bool</span> { <span class="kw">return</span> nums[i] > nums[j] })</pre>
</div>
</div>
<div class="card">
<div class="card-header">
<span class="card-title">sort.IntSlice, sort.StringSlice — ready-made Interface types</span>
<span class="card-badge badge-blue">Convenience Types</span>
</div>
<div class="code-wrap">
<pre><span class="cmt">// sort.IntSlice, sort.StringSlice, sort.Float64Slice</span>
<span class="cmt">// implement sort.Interface so you can use sort.Search on them</span>
nums := <span class="pkg">sort</span>.<span class="fn">IntSlice</span>{<span class="num">1</span>, <span class="num">3</span>, <span class="num">5</span>, <span class="num">7</span>, <span class="num">9</span>}
<span class="cmt">// Search within a sorted IntSlice</span>
i := nums.<span class="fn">Search</span>(<span class="num">5</span>) <span class="cmt">// 2 — index of 5</span>
i = nums.<span class="fn">Search</span>(<span class="num">4</span>) <span class="cmt">// 2 — insertion point for 4</span>
<span class="cmt">// You can call Sort directly on the value</span>
s := <span class="pkg">sort</span>.<span class="fn">StringSlice</span>{<span class="str">"banana"</span>, <span class="str">"apple"</span>, <span class="str">"cherry"</span>}
s.<span class="fn">Sort</span>()
<span class="cmt">// [apple banana cherry]</span></pre>
</div>
</div>
</section>
<!-- ── 5. BINARY SEARCH ──────────────────────────────── -->
<section class="section" id="search">
<div class="section-header">
<div class="section-icon icon-red">🔎</div>
<h2>Binary Search</h2>
<span class="section-tag">sort.Search · SearchInts</span>
</div>
<div class="callout warn">
<span class="callout-icon">⚠️</span>
<div><code>sort.Search</code> requires the slice to already be sorted. It returns the smallest index <code>i</code> in <code>[0, n)</code> for which <code>f(i)</code> is true. If no such index exists it returns <code>n</code>.</div>
</div>
<div class="card">
<div class="card-header">
<span class="card-title">sort.Search — generic binary search</span>
<span class="card-badge badge-red">sort.Search</span>
</div>
<div class="code-wrap">
<pre>nums := []<span class="typ">int</span>{<span class="num">1</span>, <span class="num">3</span>, <span class="num">5</span>, <span class="num">7</span>, <span class="num">9</span>, <span class="num">11</span>}
target := <span class="num">7</span>
<span class="cmt">// Find index of target in a sorted ascending slice</span>
i := <span class="pkg">sort</span>.<span class="fn">Search</span>(<span class="fn">len</span>(nums), <span class="kw">func</span>(i <span class="typ">int</span>) <span class="typ">bool</span> {
<span class="kw">return</span> nums[i] >= target
})
<span class="kw">if</span> i < <span class="fn">len</span>(nums) && nums[i] == target {
<span class="pkg">fmt</span>.<span class="fn">Printf</span>(<span class="str">"found %d at index %d\n"</span>, target, i) <span class="cmt">// found 7 at index 3</span>
} <span class="kw">else</span> {
<span class="pkg">fmt</span>.<span class="fn">Println</span>(<span class="str">"not found"</span>)
}
<span class="cmt">// Find the insertion point for a new value</span>
insert := <span class="pkg">sort</span>.<span class="fn">Search</span>(<span class="fn">len</span>(nums), <span class="kw">func</span>(i <span class="typ">int</span>) <span class="typ">bool</span> {
<span class="kw">return</span> nums[i] >= <span class="num">6</span>
})
<span class="cmt">// insert = 3 (6 would go between 5 and 7)</span></pre>
</div>
</div>
<div class="two-col">
<div class="card">
<div class="card-header">
<span class="card-title">SearchInts / SearchStrings</span>
<span class="card-badge badge-red">Convenience</span>
</div>
<div class="code-wrap">
<pre>nums := []<span class="typ">int</span>{<span class="num">2</span>, <span class="num">4</span>, <span class="num">6</span>, <span class="num">8</span>, <span class="num">10</span>}
<span class="cmt">// Returns the index; check if nums[i] == target</span>
i := <span class="pkg">sort</span>.<span class="fn">SearchInts</span>(nums, <span class="num">6</span>)
<span class="cmt">// i = 2</span>
i = <span class="pkg">sort</span>.<span class="fn">SearchInts</span>(nums, <span class="num">5</span>)
<span class="cmt">// i = 2 (insertion point for 5)</span>
words := []<span class="typ">string</span>{<span class="str">"apple"</span>, <span class="str">"banana"</span>, <span class="str">"cherry"</span>}
j := <span class="pkg">sort</span>.<span class="fn">SearchStrings</span>(words, <span class="str">"banana"</span>)
<span class="cmt">// j = 1</span></pre>
</div>
</div>
<div class="card">
<div class="card-header">
<span class="card-title">Searching a descending slice</span>
<span class="card-badge badge-gold">Descending</span>
</div>
<div class="code-wrap">
<pre><span class="cmt">// For a descending slice, flip the comparison</span>
desc := []<span class="typ">int</span>{<span class="num">10</span>, <span class="num">8</span>, <span class="num">6</span>, <span class="num">4</span>, <span class="num">2</span>}
target := <span class="num">6</span>
i := <span class="pkg">sort</span>.<span class="fn">Search</span>(<span class="fn">len</span>(desc), <span class="kw">func</span>(i <span class="typ">int</span>) <span class="typ">bool</span> {
<span class="kw">return</span> desc[i] <= target <span class="cmt">// <= for descending</span>
})
<span class="kw">if</span> i < <span class="fn">len</span>(desc) && desc[i] == target {
<span class="pkg">fmt</span>.<span class="fn">Println</span>(<span class="str">"found at index"</span>, i) <span class="cmt">// found at index 2</span>
}</pre>
</div>
</div>
</div>
</section>
<!-- ── 6. SORT VS SLICES ─────────────────────────────── -->
<section class="section" id="slices-pkg">
<div class="section-header">
<div class="section-icon icon-green">⚖️</div>
<h2>sort vs. slices package</h2>
<span class="section-tag">Go 1.21+ generics</span>
</div>
<div class="callout tip">
<span class="callout-icon">💡</span>
<div>Go 1.21 added the <code>slices</code> package with generic sorting functions. They're often more ergonomic for typed slices. Both packages coexist — use whichever reads clearer in context.</div>
</div>
<div class="two-col">
<div class="card">
<div class="card-header">
<span class="card-title">sort package (pre-1.21 style)</span>
<span class="card-badge badge-blue">sort</span>
</div>
<div class="code-wrap">
<pre>nums := []<span class="typ">int</span>{<span class="num">3</span>, <span class="num">1</span>, <span class="num">4</span>, <span class="num">1</span>, <span class="num">5</span>}
<span class="pkg">sort</span>.<span class="fn">Ints</span>(nums)
<span class="pkg">sort</span>.<span class="fn">Slice</span>(nums, <span class="kw">func</span>(i, j <span class="typ">int</span>) <span class="typ">bool</span> {
<span class="kw">return</span> nums[i] < nums[j]
})
i := <span class="pkg">sort</span>.<span class="fn">SearchInts</span>(nums, <span class="num">4</span>)</pre>
</div>
</div>
<div class="card">
<div class="card-header">
<span class="card-title">slices package (Go 1.21+, generic)</span>
<span class="card-badge badge-green">Go 1.21+</span>
</div>
<div class="code-wrap">
<pre>nums := []<span class="typ">int</span>{<span class="num">3</span>, <span class="num">1</span>, <span class="num">4</span>, <span class="num">1</span>, <span class="num">5</span>}
<span class="pkg">slices</span>.<span class="fn">Sort</span>(nums) <span class="cmt">// type-inferred</span>
<span class="pkg">slices</span>.<span class="fn">SortFunc</span>(nums, <span class="kw">func</span>(a, b <span class="typ">int</span>) <span class="typ">int</span> {
<span class="kw">return</span> <span class="pkg">cmp</span>.<span class="fn">Compare</span>(a, b) <span class="cmt">// returns -1/0/1</span>
})
i, _ := <span class="pkg">slices</span>.<span class="fn">BinarySearch</span>(nums, <span class="num">4</span>)</pre>
</div>
</div>
</div>
<div class="card">
<div class="card-header">
<span class="card-title">When to prefer slices.SortFunc</span>
<span class="card-badge badge-purple">Guidance</span>
</div>
<div class="code-wrap">
<pre><span class="kw">import</span> (
<span class="str">"cmp"</span>
<span class="str">"slices"</span>
)
<span class="kw">type</span> <span class="typ">Person</span> <span class="kw">struct</span>{ Name <span class="typ">string</span>; Age <span class="typ">int</span> }
people := []<span class="typ">Person</span>{{<span class="str">"Alice"</span>, <span class="num">30</span>}, {<span class="str">"Bob"</span>, <span class="num">25</span>}, {<span class="str">"Carol"</span>, <span class="num">30</span>}}
<span class="cmt">// slices.SortFunc takes a cmp function (returns int) not a less function (returns bool)</span>
<span class="cmt">// Use cmp.Compare for ordered types; chain with || 0 for multi-key</span>
<span class="pkg">slices</span>.<span class="fn">SortFunc</span>(people, <span class="kw">func</span>(a, b <span class="typ">Person</span>) <span class="typ">int</span> {
<span class="kw">if</span> n := <span class="pkg">cmp</span>.<span class="fn">Compare</span>(a.Age, b.Age); n != <span class="num">0</span> {
<span class="kw">return</span> n
}
<span class="kw">return</span> <span class="pkg">cmp</span>.<span class="fn">Compare</span>(a.Name, b.Name)
})
<span class="cmt">// [{Bob 25} {Alice 30} {Carol 30}]</span></pre>
</div>
</div>
</section>
<!-- ── REFERENCE TABLE ───────────────────────────────── -->
<section class="section" id="reference">
<div class="section-header">
<div class="section-icon icon-blue">📋</div>
<h2>Quick Reference</h2>
<span class="section-tag">All key functions</span>
</div>
<table class="ref-table">
<thead>
<tr>
<th>Function</th>
<th>Signature (simplified)</th>
<th>Description</th>
</tr>
</thead>
<tbody>
<tr><td>sort.Slice</td><td>(slice any, less func(i,j int) bool)</td><td>Sort any slice in-place; unstable</td></tr>
<tr><td>sort.SliceStable</td><td>(slice any, less func(i,j int) bool)</td><td>Stable sort; preserves equal element order</td></tr>
<tr><td>sort.SliceIsSorted</td><td>(slice any, less func) bool</td><td>Report whether slice is sorted by less</td></tr>
<tr><td>sort.Ints</td><td>(a []int)</td><td>Sort int slice ascending</td></tr>
<tr><td>sort.Strings</td><td>(a []string)</td><td>Sort string slice ascending</td></tr>
<tr><td>sort.Float64s</td><td>(a []float64)</td><td>Sort float64 slice ascending</td></tr>
<tr><td>sort.IntsAreSorted</td><td>(a []int) bool</td><td>True if int slice is ascending</td></tr>
<tr><td>sort.StringsAreSorted</td><td>(a []string) bool</td><td>True if string slice is ascending</td></tr>
<tr><td>sort.Sort</td><td>(data Interface)</td><td>Sort any type implementing sort.Interface</td></tr>
<tr><td>sort.Stable</td><td>(data Interface)</td><td>Stable sort on sort.Interface</td></tr>
<tr><td>sort.Reverse</td><td>(data Interface) Interface</td><td>Return reversed view of sort.Interface</td></tr>
<tr><td>sort.IsSorted</td><td>(data Interface) bool</td><td>True if data is in sorted order</td></tr>
<tr><td>sort.Search</td><td>(n int, f func(int) bool) int</td><td>Binary search: smallest i where f(i) is true</td></tr>
<tr><td>sort.SearchInts</td><td>(a []int, x int) int</td><td>Binary search for x in sorted int slice</td></tr>
<tr><td>sort.SearchStrings</td><td>(a []string, x string) int</td><td>Binary search for x in sorted string slice</td></tr>
<tr><td>sort.SearchFloat64s</td><td>(a []float64, x float64) int</td><td>Binary search for x in sorted float64 slice</td></tr>
</tbody>
</table>
</section>
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<li><a href="#slice">1 — Sorting Slices</a></li>
<li><a href="#builtins">2 — Built-in Functions</a></li>
<li><a href="#multikey">3 — Multi-Key Sorting</a></li>
<li><a href="#interface">4 — sort.Interface</a></li>
<li><a href="#search">5 — Binary Search</a></li>
<li><a href="#slices-pkg">6 — sort vs. slices</a></li>
<li><a href="#reference">99 — Quick Reference</a></li>
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