php character reverse

1. Use php’s built-in functions to implement
Test code

<code><span><span><?php</span><span>$str</span>=<span>'Hello World!'</span>;
<span>$res</span>=strrev(<span>$str</span>);
<span>echo</span><span>$res</span>.<span>'</br>'</span>;
<span>$str</span>=<span>'Hello World!你好 世界！'</span>;
<span>$res</span>=reverse(<span>$str</span>);
<span>echo</span><span>$res</span>;

<span>//自定义函数</span><span><span>function</span><span>reverse</span><span>(<span>$str</span>)</span> {</span><span>$len</span> = mb_strlen(<span>$str</span>, <span>'utf-8'</span>);
    <span>for</span> (<span>$i</span> = <span>0</span>; <span>$i</span> < <span>$len</span>; <span>$i</span>++) {
        <span>$arr</span>[] = mb_substr(<span>$str</span>, <span>$i</span>, <span>1</span>, <span>"utf-8"</span>);
    }
    <span>return</span> implode(<span>""</span>, array_reverse(<span>$arr</span>));
}
<span>?></span></code>

Run results
!dlroW olleH!
Hello Jishi!dlroW olleH

2.C language implementation

<code><span>#<strong>include</strong> <stdio.h></span><span>#<strong>include</strong><string.h></span><span>char</span> *<span>str</span>=<span>"Hello World!你好 世界！"</span>;

<span>int</span> main() {
  <span>int</span> i = strlen(<span>str</span>) - <span>1</span>;
  <span>while</span> (i>=<span>0</span>) {

        <span>if</span>(<span>str</span>[i] < <span>0</span>)
        {
                printf(<span>"%c%c%c\n"</span>, <span>str</span>[i-<span>2</span>], <span>str</span>[i-<span>1</span>],<span>str</span>[i]);
                i = i-<span>2</span>;
        }<span>else</span>{
                printf(<span>"%c\n"</span>, <span>str</span>[i]);
        }
        i--;
  }
  <span>return</span><span>0</span>;
}</code>

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The above introduces PHP character reversal, including include content. I hope it will be helpful to friends who are interested in PHP tutorials.