Check to see if word exists and replace it
<p>My goal seems simple enough. But I'm having difficulty trying it myself. I just need to SEARCH for a certain word inside a string and then replace it with another word. But I have to check to see if the word exists first. For example ,    </p>

<pre><code>$str1 = "Hello World!"

if ($str1 == "Hello World!") {
  //code to replace world with everyone
}
</code></pre>

<p>Seems simple enough?</p>

<p>Thanks</p>
