title: Filter string in C
body: <p>How can I filter a string in c? I want to remove anything that isn't <code>[a-z0-9_]</code>.</p>
  
  <pre><code>int main(int argc, char ** argv) {
     char* name = argv[1];
     // remove anything that isn't [a-z0-9_]
  
     printf("%s", name);
  }
  </code></pre>