php length or count string
<p>I am working on sorting some text, I want to count how many times a certain word occurs.</p>

<p>the text part like</p>

<blockquote>
  <p>I have no <strong>idea</strong>, you got some <strong>idea</strong>, we will work out some
  <strong>idea</strong>,  I have no <strong>idea</strong>, you got some <strong>idea</strong>, we will work out some <strong>idea</strong>,  I have no <strong>idea</strong>,you got some <strong>idea</strong>, we will work
  out some <strong>idea</strong></p>
</blockquote>

<p>how can I use php to count how many times "idea" occurred, like word "idea" occurred <strong>9</strong>
I am confused on count and length.</p>

<p>Could someone give an example please? many thanks</p>
