char s1[] = "Upper/LOWER.";
char s2[] = "mIXeD CaSe..";



/* copies s1 to s2, flips case of s2 */
 dostr (ptr1,ptr2)
 char *ptr1,*ptr2;
{
 unsigned char c;
   
 while (*ptr1 != 0) {
   c = *ptr1;
   if (c > 0x2F) {
     /* make sure it is not a special char */
     *ptr2 = c ^ 0x20; /* xor flips bit */
   } else {
     /* leave special chars alone */
     *ptr2 = c;
   }
   ptr1++;ptr2++;
  }

}

main()
{
 char c;


  printf("Before...\n");
  printf("s1: '%s'\n",s1);
  printf("s2: '%s'\n",s2);

  dostr(s1,s2);

  printf("After...\n");
  printf("s1: '%s'\n",s1);
  printf("s2: '%s'\n",s2);

}

<div align="center"><br /><script type="text/javascript"><!--
google_ad_client = "pub-7293844627074885";
//468x60, Created at 07. 11. 25
google_ad_slot = "8619794253";
google_ad_width = 468;
google_ad_height = 60;
//--></script>
<script type="text/javascript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script><br />&nbsp;</div>