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gobyexample/public/string-functions
Hana 9e216da9ef go.mod: add go.mod and move pygments to third_party 
After go1.16, go will use module mode by default,
even when the repository is checked out under GOPATH
or in a one-off directory. Add go.mod, go.sum to keep
this repo buildable without opting out of the module
mode.

> go mod init github.com/mmcgrana/gobyexample
> go mod tidy
> go mod vendor

In module mode, the 'vendor' directory is special
and its contents will be actively maintained by the
go command. pygments aren't the dependency the go will
know about, so it will delete the contents from vendor
directory. Move it to `third_party` directory now.

And, vendor the blackfriday package.

Note: the tutorial contents are not affected by the
change in go1.16 because all the examples in this
tutorial ask users to run the go command with the
explicit list of files to be compiled (e.g.
`go run hello-world.go` or `go build command-line-arguments.go`).
When the source list is provided, the go command does
not have to compute the build list and whether it's
running in GOPATH mode or module mode becomes irrelevant.
2021-02-15 16:45:26 -05:00

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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example: String Functions</title>
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</head>
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<body>
<div class="example" id="string-functions">
<h2><a href="./">Go by Example</a>: String Functions</h2>
<table>
<tr>
<td class="docs">
<p>The standard library&rsquo;s <code>strings</code> package provides many
useful string-related functions. Here are some examples
to give you a sense of the package.</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<a href="http://play.golang.org/p/fZ_FqN5WlSz"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
<span class="s">&quot;fmt&quot;</span>
<span class="nx">s</span> <span class="s">&quot;strings&quot;</span>
<span class="p">)</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>We alias <code>fmt.Println</code> to a shorter name as we&rsquo;ll use
it a lot below.</p>
</td>
<td class="code leading">
<div class="highlight"><pre><span class="kd">var</span> <span class="nx">p</span> <span class="p">=</span> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Here&rsquo;s a sample of the functions available in
<code>strings</code>. Since these are functions from the
package, not methods on the string object itself,
we need pass the string in question as the first
argument to the function. You can find more
functions in the <a href="http://golang.org/pkg/strings/"><code>strings</code></a>
package docs.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">p</span><span class="p">(</span><span class="s">&quot;Contains: &quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Contains</span><span class="p">(</span><span class="s">&quot;test&quot;</span><span class="p">,</span> <span class="s">&quot;es&quot;</span><span class="p">))</span>
<span class="nx">p</span><span class="p">(</span><span class="s">&quot;Count: &quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Count</span><span class="p">(</span><span class="s">&quot;test&quot;</span><span class="p">,</span> <span class="s">&quot;t&quot;</span><span class="p">))</span>
<span class="nx">p</span><span class="p">(</span><span class="s">&quot;HasPrefix: &quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">HasPrefix</span><span class="p">(</span><span class="s">&quot;test&quot;</span><span class="p">,</span> <span class="s">&quot;te&quot;</span><span class="p">))</span>
<span class="nx">p</span><span class="p">(</span><span class="s">&quot;HasSuffix: &quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">HasSuffix</span><span class="p">(</span><span class="s">&quot;test&quot;</span><span class="p">,</span> <span class="s">&quot;st&quot;</span><span class="p">))</span>
<span class="nx">p</span><span class="p">(</span><span class="s">&quot;Index: &quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Index</span><span class="p">(</span><span class="s">&quot;test&quot;</span><span class="p">,</span> <span class="s">&quot;e&quot;</span><span class="p">))</span>
<span class="nx">p</span><span class="p">(</span><span class="s">&quot;Join: &quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Join</span><span class="p">([]</span><span class="kt">string</span><span class="p">{</span><span class="s">&quot;a&quot;</span><span class="p">,</span> <span class="s">&quot;b&quot;</span><span class="p">},</span> <span class="s">&quot;-&quot;</span><span class="p">))</span>
<span class="nx">p</span><span class="p">(</span><span class="s">&quot;Repeat: &quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Repeat</span><span class="p">(</span><span class="s">&quot;a&quot;</span><span class="p">,</span> <span class="mi">5</span><span class="p">))</span>
<span class="nx">p</span><span class="p">(</span><span class="s">&quot;Replace: &quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Replace</span><span class="p">(</span><span class="s">&quot;foo&quot;</span><span class="p">,</span> <span class="s">&quot;o&quot;</span><span class="p">,</span> <span class="s">&quot;0&quot;</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">))</span>
<span class="nx">p</span><span class="p">(</span><span class="s">&quot;Replace: &quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Replace</span><span class="p">(</span><span class="s">&quot;foo&quot;</span><span class="p">,</span> <span class="s">&quot;o&quot;</span><span class="p">,</span> <span class="s">&quot;0&quot;</span><span class="p">,</span> <span class="mi">1</span><span class="p">))</span>
<span class="nx">p</span><span class="p">(</span><span class="s">&quot;Split: &quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Split</span><span class="p">(</span><span class="s">&quot;a-b-c-d-e&quot;</span><span class="p">,</span> <span class="s">&quot;-&quot;</span><span class="p">))</span>
<span class="nx">p</span><span class="p">(</span><span class="s">&quot;ToLower: &quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">ToLower</span><span class="p">(</span><span class="s">&quot;TEST&quot;</span><span class="p">))</span>
<span class="nx">p</span><span class="p">(</span><span class="s">&quot;ToUpper: &quot;</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">ToUpper</span><span class="p">(</span><span class="s">&quot;test&quot;</span><span class="p">))</span>
<span class="nx">p</span><span class="p">()</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Not part of <code>strings</code>, but worth mentioning here, are
the mechanisms for getting the length of a string in
bytes and getting a byte by index.</p>
</td>
<td class="code leading">
<div class="highlight"><pre> <span class="nx">p</span><span class="p">(</span><span class="s">&quot;Len: &quot;</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="s">&quot;hello&quot;</span><span class="p">))</span>
<span class="nx">p</span><span class="p">(</span><span class="s">&quot;Char:&quot;</span><span class="p">,</span> <span class="s">&quot;hello&quot;</span><span class="p">[</span><span class="mi">1</span><span class="p">])</span>
<span class="p">}</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
<p>Note that <code>len</code> and indexing above work at the byte level.
Go uses UTF-8 encoded strings, so this is often useful
as-is. If you&rsquo;re working with potentially multi-byte
characters you&rsquo;ll want to use encoding-aware operations.
See <a href="https://blog.golang.org/strings">strings, bytes, runes and characters in Go</a>
for more information.</p>
</td>
<td class="code empty">
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
</td>
<td class="code leading">
<div class="highlight"><pre><span class="gp">$</span> go run string-functions.go
<span class="go">Contains: true</span>
<span class="go">Count: 2</span>
<span class="go">HasPrefix: true</span>
<span class="go">HasSuffix: true</span>
<span class="go">Index: 1</span>
<span class="go">Join: a-b</span>
<span class="go">Repeat: aaaaa</span>
<span class="go">Replace: f00</span>
<span class="go">Replace: f0o</span>
<span class="go">Split: [a b c d e]</span>
<span class="go">ToLower: test</span>
<span class="go">ToUpper: TEST</span>
</pre></div>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code">
<div class="highlight"><pre><span class="go">Len: 5</span>
<span class="go">Char: 101</span>
</pre></div>
</td>
</tr>
</table>
<p class="next">
Next example: <a href="string-formatting">String Formatting</a>.
</p>
<p class="footer">
by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/string-functions">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
</p>
</div>
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