title: check if the value is decimal numbre (not a number as character)
body: <p>I want to check if the value that the user entered is integer number (<strong>I mean an integer, not a  number as character (like char)</strong>).<br>
  I have used <code>isdigit</code> function, and <code>is...</code> sisters, but does not work good.</p>
  
  <p><strong>For example:</strong></p>
  
  <pre><code>int digits = 220; // Or scanf("%d", digits); Or any way to take the input from user
  if(digits == `integer number`){
     // do things
  }else{
     // do things
  }
  </code></pre>