一、实现字符串的逆序

在go中，字符串要根据索引获取值是需要转为字节的。接下来我们看一个实现代码

代码应该都看的明白，下面咔咔用图解来帮助解释一下

<span style="display: block; background: url(https://imgkr.cn-bj.ufileos.com/97e4eed2-a992-4976-acf0-ccb6fb34d308.png); height: 30px; width: 100%; background-size: 40px; background-repeat: no-repeat; background-color: #272822; margin-bottom: -7px; border-radius: 5px; background-position: 10px 10px;"></span><code class="hljs" style="overflow-x: auto; padding: 16px; color: #ddd; display: -webkit-box; font-family: Operator Mono, Consolas, Monaco, Menlo, monospace; font-size: 12px; -webkit-overflow-scrolling: touch; letter-spacing: 0px; padding-top: 15px; background: #272822; border-radius: 5px;"><span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">package</span> main<br/><br/><span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">import</span> (<br/> <span class="hljs-string" style="color: #a6e22e; line-height: 26px;">"fmt"</span><br/>)<br/><br/><span class="hljs-function" style="line-height: 26px;"><span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">func</span> <span class="hljs-title" style="color: #a6e22e; font-weight: bold; line-height: 26px;">stringReverse</span><span class="hljs-params" style="line-height: 26px;">()</span></span> {<br/> <span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">var</span> str = <span class="hljs-string" style="color: #a6e22e; line-height: 26px;">"Hello"</span><br/> <span class="hljs-comment" style="color: #75715e; line-height: 26px;">// 字符串转字节</span><br/> <span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">var</span> bytes []<span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">byte</span> = []<span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">byte</span>(str)<br/> <span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">for</span> i := <span class="hljs-number" style="line-height: 26px;">0</span>; i < <span class="hljs-built_in" style="color: #a6e22e; line-height: 26px;">len</span>(str)/<span class="hljs-number" style="line-height: 26px;">2</span>; i++ {<br/>  <span class="hljs-comment" style="color: #75715e; line-height: 26px;">// 定义一个变量存放从后往前的值</span><br/>  tmp := bytes[<span class="hljs-built_in" style="color: #a6e22e; line-height: 26px;">len</span>(str)-i<span class="hljs-number" style="line-height: 26px;">-1</span>]<br/>  <span class="hljs-comment" style="color: #75715e; line-height: 26px;">// 从后往前的值跟从前往后的值调换</span><br/>  bytes[<span class="hljs-built_in" style="color: #a6e22e; line-height: 26px;">len</span>(str)-i<span class="hljs-number" style="line-height: 26px;">-1</span>] = bytes[i]<br/>  <span class="hljs-comment" style="color: #75715e; line-height: 26px;">// 从前往后的值跟从后往前的值进行调换</span><br/>  bytes[i] = tmp<br/> }<br/> str = <span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">string</span>(bytes)<br/> fmt.Println(str)<br/>}<br/></code>

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这段代码可以看到循环的最大次数就是将字符串的长度除了2

在这副图中我们可以看到第一次循环时是将第一字符串跟最后一个字符串进行调换

第二次循环时将第二个值跟倒数第二值进行调换

这就是这块代码的意义所在

先将索引最后的字符串的值拿出来

接着让最后索引的字符串跟第一个索引字符串相等也就是上图中第一个步骤让最后一个值跟等于第一个值

然后把第一个索引的字符串改为我们第一步保存的值同理让第一个值等于最后一个值

在go中还有好几种实现这个过程，这里咔咔在提供一种供大家参考

这种方式需要引入包strings，也是官方推荐的一种方式

<span style="display: block; background: url(https://imgkr.cn-bj.ufileos.com/97e4eed2-a992-4976-acf0-ccb6fb34d308.png); height: 30px; width: 100%; background-size: 40px; background-repeat: no-repeat; background-color: #272822; margin-bottom: -7px; border-radius: 5px; background-position: 10px 10px;"></span><code class="hljs" style="overflow-x: auto; padding: 16px; color: #ddd; display: -webkit-box; font-family: Operator Mono, Consolas, Monaco, Menlo, monospace; font-size: 12px; -webkit-overflow-scrolling: touch; letter-spacing: 0px; padding-top: 15px; background: #272822; border-radius: 5px;"><span class="hljs-function" style="line-height: 26px;"><span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">func</span> <span class="hljs-title" style="color: #a6e22e; font-weight: bold; line-height: 26px;">stringReverse1</span><span class="hljs-params" style="line-height: 26px;">()</span></span> {<br/> <span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">var</span> str = <span class="hljs-string" style="color: #a6e22e; line-height: 26px;">"hello"</span><br/> <span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">var</span> bytes []<span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">byte</span> = []<span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">byte</span>(str)<br/> <span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">var</span> build strings.Builder<br/> <span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">for</span> i := <span class="hljs-number" style="line-height: 26px;">0</span>; i < <span class="hljs-built_in" style="color: #a6e22e; line-height: 26px;">len</span>(bytes); i++ {<br/>  i2 := bytes[<span class="hljs-built_in" style="color: #a6e22e; line-height: 26px;">len</span>(bytes)-i<span class="hljs-number" style="line-height: 26px;">-1</span>]<br/>  build.WriteString(<span class="hljs-keyword" style="color: #f92672; font-weight: bold; line-height: 26px;">string</span>(i2))<br/> }<br/> s3 := build.String()<br/> fmt.Println(s3)<br/>}<br/></code>

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执行俩个代码，检测是否可行