substr_count

名稱:substr_count

分類:字符串

所屬語言:php

一句話介紹:計算子串在字符串中出現的次數。

實例

例子1

計算"Shanghai" 在字符串中出現的次數：

 <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>

親自試一試

例子2

使用所有的參數：

 <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() 來返回字符串長度</span>
<span class="token keyword">echo</span> <span class="token function">substr_count</span> <span class="token punctuation">(</span> <span class="token variable">$str</span> <span class="token punctuation">,</span> <span class="token string double-quoted-string">"is"</span> <span class="token punctuation">)</span> <span class="token operator">.</span> <span class="token string double-quoted-string">"<br>"</span> <span class="token punctuation">;</span> <span class="token comment">// 字符串中"is" 出現的次數</span>
<span class="token keyword">echo</span> <span class="token function">substr_count</span> <span class="token punctuation">(</span> <span class="token variable">$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">// 字符串縮減為"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">$str</span> <span class="token punctuation">,</span> <span class="token string double-quoted-string">"is"</span> <span class="token punctuation">,</span> <span class="token number">3</span> <span class="token punctuation">)</span> <span class="token operator">.</span> <span class="token string double-quoted-string">"<br>"</span> <span class="token punctuation">;</span> <span class="token comment">// 字符串縮減為"s is nice"</span>
<span class="token keyword">echo</span> <span class="token function">substr_count</span> <span class="token punctuation">(</span> <span class="token variable">$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">// 字符串縮減為"si"</span>
<span class="token delimiter important">?></span></span>

親自試一試

例子3

重疊的子串：

 <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">// 此函數不會對重疊的子字符串計數</span>
<span class="token delimiter important">?></span></span>

親自試一試

例子4

如果start和length參數超過字符串長度，則該函數會輸出一個警告：

 <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>

因為長度值超過字符串的長度（3 + 9 大於12），使用會輸出一個警告。