title: char * vs unsigned char* what is the difference?
body: <p>In Linux with c , I didn't understant what is the diffrence between <code>char*</code> and <code>unsigned char*</code> When I reading/writing binary buffer ?</p>
  
  <p>When I must not using <code>char*</code> and need to use <code>unsigned char*</code>?</p>