substr_count

名称:substr_count

分类:字符串

所属语言:php

一句话介绍:计算子串在字符串中出现的次数。

实例

例子 1

计算 "Shanghai" 在字符串中出现的次数：

<span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token keyword">echo</span> <span class="token function">substr_count</span><span class="token punctuation">(</span><span class="token string double-quoted-string">"I love Shanghai. Shanghai is the biggest city in china."</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"Shanghai"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token delimiter important">?></span></span>

亲自试一试

例子 2

使用所有的参数：

<span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token variable">$str</span> <span class="token operator">=</span> <span class="token string double-quoted-string">"This is nice"</span><span class="token punctuation">;</span>
<span class="token keyword">echo</span> <span class="token function">strlen</span><span class="token punctuation">(</span><span class="token variable">$str</span><span class="token punctuation">)</span><span class="token operator">.</span><span class="token string double-quoted-string">"<br>"</span><span class="token punctuation">;</span> <span class="token comment">// 使用 strlen() 来返回字符串长度</span>
<span class="token keyword">echo</span> <span class="token function">substr_count</span><span class="token punctuation">(</span><span class="token variable">$str</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"is"</span><span class="token punctuation">)</span><span class="token operator">.</span><span class="token string double-quoted-string">"<br>"</span><span class="token punctuation">;</span> <span class="token comment">// 字符串中 "is" 出现的次数</span>
<span class="token keyword">echo</span> <span class="token function">substr_count</span><span class="token punctuation">(</span><span class="token variable">$str</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"is"</span><span class="token punctuation">,</span><span class="token number">2</span><span class="token punctuation">)</span><span class="token operator">.</span><span class="token string double-quoted-string">"<br>"</span><span class="token punctuation">;</span> <span class="token comment">// 字符串缩减为 "is is nice"</span>
<span class="token keyword">echo</span> <span class="token function">substr_count</span><span class="token punctuation">(</span><span class="token variable">$str</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"is"</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">)</span><span class="token operator">.</span><span class="token string double-quoted-string">"<br>"</span><span class="token punctuation">;</span> <span class="token comment">// 字符串缩减为 "s is nice"</span>
<span class="token keyword">echo</span> <span class="token function">substr_count</span><span class="token punctuation">(</span><span class="token variable">$str</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"is"</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">)</span><span class="token operator">.</span><span class="token string double-quoted-string">"<br>"</span><span class="token punctuation">;</span> <span class="token comment">// 字符串缩减为 "s i"</span>
<span class="token delimiter important">?></span></span>

亲自试一试

例子 3

重叠的子串：

<span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token variable">$str</span> <span class="token operator">=</span> <span class="token string double-quoted-string">"abcabcab"</span><span class="token punctuation">;</span>
<span class="token keyword">echo</span> <span class="token function">substr_count</span><span class="token punctuation">(</span><span class="token variable">$str</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"abcab"</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 此函数不会对重叠的子字符串计数</span>
<span class="token delimiter important">?></span></span>

亲自试一试

例子 4

如果 start 和 length 参数超过字符串长度，则该函数会输出一个警告：

<span class="token php language-php"><span class="token delimiter important"><?php</span>
<span class="token keyword">echo</span> <span class="token variable">$str</span> <span class="token operator">=</span> <span class="token string double-quoted-string">"This is nice"</span><span class="token punctuation">;</span>
<span class="token function">substr_count</span><span class="token punctuation">(</span><span class="token variable">$str</span><span class="token punctuation">,</span><span class="token string double-quoted-string">"is"</span><span class="token punctuation">,</span><span class="token number">3</span><span class="token punctuation">,</span><span class="token number">9</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token delimiter important">?></span></span>

因为长度值超过字符串的长度（3 + 9 大于 12），使用会输出一个警告。