title: Check if input is a correct integer
body: <p>I have a little problem with checking my input. I know that there a already similar questions but sincerly it does not solve my problem. I'm already using one of the suggestions from the other questions and it does not work.</p>
  
  <pre><code>#include &lt;iostream&gt;
  #include &lt;stdio.h&gt;
  #include &lt;ctype.h&gt;
  
  
  int main ()
  {
   int a;
  
   printf("Please type in your number: ");
   scanf_s("%d", &amp;a);
  
   if(isdigit(a))
   {
      printf("True.");
   }
   else
   {
   printf("False.");
   }
  
   std::cin.get();
   std::cin.get();
  
   return 0;
  
  }
  </code></pre>
  
  <p>I don't know what i'm doing wrong but my output is always "False" when i type in a number. When i type in a letter the compiler has an error.</p>