title: How do I replace certain parts of my string?
body: <p>How can I replace a certain part of my string with another one?</p>
  
  <p>Input string:</p>
  
  <pre><code>"Hello, my name is Santa"
  </code></pre>
  
  <p>How can I change all <code>a</code>'s in my string with something else?</p>
  
  <p>I think I need a <code>foreach</code> loop, but I'm unsure how to use it.</p>