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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example မြန်မာဘာသာ: Strings and Runes</title>
<link rel=stylesheet href="site.css">
</head>
<script>
onkeydown = (e) => {
if (e.key == "ArrowLeft") {
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<body>
<div class="example" id="strings-and-runes">
<h2><a href="./">Go by Example မြန်မာဘာသာ</a>: Strings and Runes</h2>
<table>
<tr>
<td class="docs">
<p>Go string ဆိုတာ read-only byte slice တစ်ခုဖြစ်ပါတယ်။ Go language နဲ့
standard library က string တွေကို encoded <a href="https://en.wikipedia.org/wiki/UTF-8">UTF-8</a> (containers of text) အဖြစ်ဖြစ်
special အနေဖြင့်အသုံးပြုပါတယ်။
တခြား language တွေမှာ string တွေက “character” တွေနဲ့ ဖွဲ့စည်းထားပါတယ်။
Go မှာတော့ character ဆိုတဲ့ သဘောတရားကို <code>rune</code> လို့ခေါ်ပါတယ် -
Unicode code point တစ်ခုကို ကိုယ်စားပြုတဲ့ integer တစ်ခုပါ။
<a href="https://go.dev/blog/strings">ဒီ Go blog post</a> က ဒီအကြောင်းအရာနှင့်ပတ်သတ်တာကိုသေချာ မိတ်ဆက်ထားပါတယ်။</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/2ycQ4YDwTk-"><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="p">(</span>
<span class="s">"fmt"</span>
<span class="s">"unicode/utf8"</span>
<span class="p">)</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><code>s</code> က ထိုင်းဘာသာစကားဖြင့် “hello” လို့ရေးထားတဲ့ literal value ကို assign လုပ်ထားတဲ့
<code>string</code> တစ်ခုဖြစ်ပါတယ်။ Go string literal တွေဟာ UTF-8 နဲ့
encode လုပ်ထားတဲ့ စာသားတွေဖြစ်ပါတယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">const</span> <span class="nx">s</span> <span class="p">=</span> <span class="s">"สวัสดี"</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>String တွေဟာ <code>[]byte</code> နဲ့ တူညီတဲ့အတွက်၊ ဒီကုဒ်က
သိမ်းဆည်းထားတဲ့ raw byte တွေရဲ့ အရေအတွက်ကို ပြပါလိမ့်မယ်။</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>String ထဲကို indexing လုပ်ခြင်းဟာ တစ်ခုချင်းစီရဲ့ index မှာရှိတဲ့ raw byte တန်ဖိုးတွေကို ထုတ်ပေးပါတယ်။
ဒီ loop က <code>s</code> ထဲမှာပါတဲ့ code point တွေကို ဖွဲ့စည်းထားတဲ့ byte အားလုံးရဲ့ hex တန်ဖိုးတွေကို ထုတ်ပေးပါတယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<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="nb">len</span><span class="p">(</span><span class="nx">s</span><span class="p">);</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Printf</span><span class="p">(</span><span class="s">"%x "</span><span class="p">,</span> <span class="nx">s</span><span class="p">[</span><span class="nx">i</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>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>String တစ်ခုထဲမှာ <em>rune</em> ဘယ်နှစ်ခုပါလဲဆိုတာ ရေတွက်ဖို့ <code>utf8</code> package ကို သုံးနိုင်ပါတယ်။
<code>RuneCountInString</code> ရဲ့ run-time က string ရဲ့ အရွယ်အစားပေါ်မှာ မူတည်ပါတယ်။
ဘာကြောင့်လဲဆိုတော့ UTF-8 rune တိုင်းကို တစ်ခုချင်းစီ decode လုပ်ရလို့ပါ။
ထိုင်းစာလုံးအချို့ဟာ UTF-8 code point တွေအများကြီးနဲ့ ဖွဲ့စည်းထားတာမို့
ဒီရေတွက်မှုရဲ့ ရလဒ်က အံ့ဩစရာ (surprising) ဖြစ်နိုင်ပါတယ်။</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">"Rune count:"</span><span class="p">,</span> <span class="nx">utf8</span><span class="p">.</span><span class="nf">RuneCountInString</span><span class="p">(</span><span class="nx">s</span><span class="p">))</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>range</code> loop က string တွေကို
<code>rune</code> တိုင်းကို သူ့ရဲ့ string ထဲက offset နဲ့အတူ decode လုပ်ပီး handle လုပ်ပါတယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="k">for</span> <span class="nx">idx</span><span class="p">,</span> <span class="nx">runeValue</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">s</span> <span class="p">{</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Printf</span><span class="p">(</span><span class="s">"%#U starts at %d\n"</span><span class="p">,</span> <span class="nx">runeValue</span><span class="p">,</span> <span class="nx">idx</span><span class="p">)</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>utf8.DecodeRuneInString</code> function ကို အသုံးပြုပြီးလည်း
အထက်ကလိုမျိုး iteration လုပ်လို့ရပါတယ်။</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">"\nUsing DecodeRuneInString"</span><span class="p">)</span>
<span class="k">for</span> <span class="nx">i</span><span class="p">,</span> <span class="nx">w</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</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="nx">i</span> <span class="o">+=</span> <span class="nx">w</span> <span class="p">{</span>
<span class="nx">runeValue</span><span class="p">,</span> <span class="nx">width</span> <span class="o">:=</span> <span class="nx">utf8</span><span class="p">.</span><span class="nf">DecodeRuneInString</span><span class="p">(</span><span class="nx">s</span><span class="p">[</span><span class="nx">i</span><span class="p">:])</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nf">Printf</span><span class="p">(</span><span class="s">"%#U starts at %d\n"</span><span class="p">,</span> <span class="nx">runeValue</span><span class="p">,</span> <span class="nx">i</span><span class="p">)</span>
<span class="nx">w</span> <span class="p">=</span> <span class="nx">width</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>ဒါက <code>rune</code> တန်ဖိုးတစ်ခုကို function ဆီသို့ pass လုပ်တာကို ပြသပါတယ်။</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nf">examineRune</span><span class="p">(</span><span class="nx">runeValue</span><span class="p">)</span>
<span class="p">}</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>Single quote နဲ့ ဝိုင်းထားတဲ့ value တွေက rune literals ဖြစ်ပါတယ်။
<code>rune</code> တန်ဖိုးတစ်ခုကို rune literal နဲ့ တိုက်ရိုက်နှိုင်းယှဉ်လို့ရပါတယ်။</p>
</td>
<td class="code leading">
<pre class="chroma"><span class="kd">func</span> <span class="nf">examineRune</span><span class="p">(</span><span class="nx">r</span> <span class="kt">rune</span><span class="p">)</span> <span class="p">{</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code">
<pre class="chroma"> <span class="k">if</span> <span class="nx">r</span> <span class="o">==</span> <span class="sc">'t'</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">"found tee"</span><span class="p">)</span>
<span class="p">}</span> <span class="k">else</span> <span class="k">if</span> <span class="nx">r</span> <span class="o">==</span> <span class="sc">'ส'</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">"found so sua"</span><span class="p">)</span>
<span class="p">}</span>
<span class="p">}</span>
</pre>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="gp">$</span> go run strings-and-runes.go
<span class="go">Len: 18
</span><span class="go">e0 b8 aa e0 b8 a7 e0 b8 b1 e0 b8 aa e0 b8 94 e0 b8 b5
</span><span class="go">Rune count: 6
</span><span class="go">U+0E2A 'ส' starts at 0
</span><span class="go">U+0E27 'ว' starts at 3
</span><span class="go">U+0E31 'ั' starts at 6
</span><span class="go">U+0E2A 'ส' starts at 9
</span><span class="go">U+0E14 'ด' starts at 12
</span><span class="go">U+0E35 'ี' starts at 15</span></pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code">
<pre class="chroma"><span class="go">Using DecodeRuneInString
</span><span class="go">U+0E2A 'ส' starts at 0
</span><span class="go">found so sua
</span><span class="go">U+0E27 'ว' starts at 3
</span><span class="go">U+0E31 'ั' starts at 6
</span><span class="go">U+0E2A 'ส' starts at 9
</span><span class="go">found so sua
</span><span class="go">U+0E14 'ด' starts at 12
</span><span class="go">U+0E35 'ี' starts at 15</span></pre>
</td>
</tr>
</table>
<p class="next">
နောက်ဥပမာ: <a href="structs">Structs</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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