title: How to write own isnumber() function?
body: <p>I'm new to C and I'm thinking how to write this function myself. I take a parameter from command line, so it is stored in argv array and I want to decide whether it is or isn't number. What is the easiest way to do this?</p>
  
  <p>Thank you</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  
  int isNumber(int *param)
  {   
      if (*param &gt; 0 &amp;&amp; *param &lt; 128)
          return 1;
      return 0;
  } 
  
  int main(int argc, char *argv[])
  {
      if (argc == 2)
          isNumber(argv[1]);
      else printf("Not enought parameters.");
  
      return 0;
  }
  </code></pre>