title: How to insert a string inside another string?
body: <p>Just looked at function </p>
  
  <pre><code>str_pad($input, $pad_length, $pad_str, [STR_PAD_RIGHT, STR_PAD_LEFT, or STR_PAD_BOTH])
  </code></pre>
  
  <p>which helps to pad some string on left, right or on both sides of a given input. </p>
  
  <p>Is there any php function which I can use to insert a string inside an input string?</p>
  
  <p>for example .. </p>
  
  <pre><code>$input = "abcdef";
  $pad_str = "@";
  </code></pre>
  
  <p>so if I give insert index 3, it inserts <code>"@"</code> after first 3 left most characters and <code>$input</code> becomes <code>"abc@def"</code>.</p>
  
  <p>thanks </p>