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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example မြန်မာဘာသာ: Slices</title>
<link rel=stylesheet href="site.css">
</head>
<script>
onkeydown = (e) => {
if (e.key == "ArrowLeft") {
window.location.href = 'arrays';
}
if (e.key == "ArrowRight") {
window.location.href = 'maps';
}
}
</script>
<body>
<div class="example" id="slices">
<h2><a href="./">Go by Example မြန်မာဘာသာ</a>: Slices</h2>
<table>
<tr>
<td class="docs">
<p><em>Slices</em> data type က Go မှာတော်တော်အသုံးဝင်တယ်။
array ထက်တောင်ပိုပီးအသုံးဝင်တယ်။</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<a href="https://go.dev/play/p/S0kazAYjN7B"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kn">import</span> <span class="s">"fmt"</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kd">func</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>arrays နဲ့မတူတာက slices မှာ elements တွေရဲ့ type တွေဘဲသတ်မှတ်ပေးစရာလိုတယ်။
ဘယ်လောက် size ဘာညာသတ်မှတ်စရာမလိုဘူး။
အစကထဲကဘယ်လောက် size ရှိမယ်ဘာညာသိစရာမလိုဘူး။
ဒီ code မှာဆိုရင် buildin <code>make</code> ကိုသုံးပီးတော့ length 3 ခုပါတဲ့ slice တခုဖန်တီးလိုက်တယ်။
(default အနေနဲ့ zero value သတ်မှတ်သွားပါလိမ့်မယ်)</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">s</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">string</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"emp:"</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>set/get တွေကတော့ array မှာလိုပါဘဲ</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">s</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="p">=</span> <span class="s">"a"</span>
<span class="nx">s</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span> <span class="p">=</span> <span class="s">"b"</span>
<span class="nx">s</span><span class="p">[</span><span class="mi">2</span><span class="p">]</span> <span class="p">=</span> <span class="s">"c"</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"set:"</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"get:"</span><span class="p">,</span> <span class="nx">s</span><span class="p">[</span><span class="mi">2</span><span class="p">])</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>len</code> ကတော့ သိတဲ့အတိုင်း slice ရဲ့ length ကိုပြန်ပေးပါလိမ့်မယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"len:"</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="nx">s</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>slices က array ထက်ပိုအသုံးဝင်တဲ့ baisc operations တွေပါတယ်။
နမူနာပြောရမယ်ဆိုရင် <code>append</code> ပေါ့။ <code>append</code> မှာတခုသတိထားရမှာက
return value ကို accept လုပ်ရမယ်၊ ဘာလို့လဲဆိုရင်တော့ slice value အသစ်ပြန်ရချင်ရမှာမလို့ပါ။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">s</span> <span class="p">=</span> <span class="nb">append</span><span class="p">(</span><span class="nx">s</span><span class="p">,</span> <span class="s">"d"</span><span class="p">)</span>
<span class="nx">s</span> <span class="p">=</span> <span class="nb">append</span><span class="p">(</span><span class="nx">s</span><span class="p">,</span> <span class="s">"e"</span><span class="p">,</span> <span class="s">"f"</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"apd:"</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>slice တခုကနေပီးတော့ နောက်တခုကို copy ကူးလို့ရပါတယ်။
အခုဒီကုဒ်မှာဆိုရင် <code>make</code> ကိုသုံးပြီးတော့ s နဲ့ len တူတဲ့ slice တခုကိုတည်ဆောက်လိုက်ပါတယ်</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="c1">//ပီးတော့ `s` ကနေပီးတော့ `c` ထဲကို copy ကူးလိုက်တာပါ။
</span><span class="c1"></span> <span class="nx">c</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">string</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="nx">s</span><span class="p">))</span>
<span class="nb">copy</span><span class="p">(</span><span class="nx">c</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"cpy:"</span><span class="p">,</span> <span class="nx">c</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>Slices မှာ “slice” operator ကိုဒီလို <code>slice[low:high]</code> syntax နှင့်သုံးပီးတော့
ကိုယ်လိုချင်တဲ့အပိုင်းကိုဘဲဖြတ်ပီးသုံးနိုင်ပါတယ်။ ဒီဥပမာမှာဆိုရင်ကျနော်တို့က s slice ရဲ့အစ
<code>s[2]</code> ကနေပီးတော့ <code>s[4]</code> ထိ item တွေကိုဘဲဖြတ်ပီးသုံးနိုင်ပါတယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">l</span> <span class="o">:=</span> <span class="nx">s</span><span class="p">[</span><span class="mi">2</span><span class="p">:</span><span class="mi">5</span><span class="p">]</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"sl1:"</span><span class="p">,</span> <span class="nx">l</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>ဒီဥမာကတော့ အစကနေပီးတော့ <code>s[5]</code> မတိုင်ခင်ထိ ဖြတ်ပီးသုံးပြထားတာပါ။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">l</span> <span class="p">=</span> <span class="nx">s</span><span class="p">[:</span><span class="mi">5</span><span class="p">]</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"sl2:"</span><span class="p">,</span> <span class="nx">l</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>ဒီဥပမာကတော့ <code>s[2]</code> ကနေနောက်ပိုင်းအကုန်လုံးကိုဘဲဖြတ်ပီးသုံးပြထားတာပါ။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">l</span> <span class="p">=</span> <span class="nx">s</span><span class="p">[</span><span class="mi">2</span><span class="p">:]</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"sl3:"</span><span class="p">,</span> <span class="nx">l</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>slice ကို line တခုထဲနှင့် initialize လုပ်ပီးတော့လဲအသုံးပြုနိုင်တယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">t</span> <span class="o">:=</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">"g"</span><span class="p">,</span> <span class="s">"h"</span><span class="p">,</span> <span class="s">"i"</span><span class="p">}</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"dcl:"</span><span class="p">,</span> <span class="nx">t</span><span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>Slices တွေကို slice ထဲထည့်ပီး multi-dimensional data structure အဖြစ်
အသုံးပြုနိုင်တယ်။ ပုံမှန် multi-dimensional array တွေနဲ့မတူတာကသူက
fixed length ဖြစ်မနေဘဲ အမျိုးမျိုးပြောင်းလဲနေနိုင်ပါတယ်။</p>
</td>
<td class="code">
<pre class="chroma">
<span class="nx">twoD</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([][]</span><span class="kt">int</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span>
<span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</span> <span class="p"><</span> <span class="mi">3</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
<span class="nx">innerLen</span> <span class="o">:=</span> <span class="nx">i</span> <span class="o">+</span> <span class="mi">1</span>
<span class="nx">twoD</span><span class="p">[</span><span class="nx">i</span><span class="p">]</span> <span class="p">=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">int</span><span class="p">,</span> <span class="nx">innerLen</span><span class="p">)</span>
<span class="k">for</span> <span class="nx">j</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">j</span> <span class="p"><</span> <span class="nx">innerLen</span><span class="p">;</span> <span class="nx">j</span><span class="o">++</span> <span class="p">{</span>
<span class="nx">twoD</span><span class="p">[</span><span class="nx">i</span><span class="p">][</span><span class="nx">j</span><span class="p">]</span> <span class="p">=</span> <span class="nx">i</span> <span class="o">+</span> <span class="nx">j</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="s">"2d: "</span><span class="p">,</span> <span class="nx">twoD</span><span class="p">)</span>
<span class="p">}</span>
</pre>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
<p>Note that while slices are different types than arrays,
they are rendered similarly by <code>fmt.Println</code>.</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="gp">$</span> go run slices.go
<span class="go">emp: [ ]
</span><span class="go">set: [a b c]
</span><span class="go">get: c
</span><span class="go">len: 3
</span><span class="go">apd: [a b c d e f]
</span><span class="go">cpy: [a b c d e f]
</span><span class="go">sl1: [c d e]
</span><span class="go">sl2: [a b c d e]
</span><span class="go">sl3: [c d e f]
</span><span class="go">dcl: [g h i]
</span><span class="go">2d: [[0] [1 2] [2 3 4]]</span></pre>
</td>
</tr>
<tr>
<td class="docs">
<p>Check out this <a href="https://go.dev/blog/slices-intro">great blog post</a>
by the Go team for more details on the design and
implementation of slices in Go.</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
<p>Now that we’ve seen arrays and slices we’ll look at
Go’s other key builtin data structure: maps.</p>
</td>
<td class="code empty">
</td>
</tr>
</table>
<p class="next">
နောက်ဥပမာ: <a href="maps">Maps</a>.
</p>
<p class="footer">
by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> နှင့် <a href="https://eli.thegreenplace.net">Eli Bendersky</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
</p>
</div>
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