<p> <code><body onload="f.a.select();"><br /><?php<br />echo 'a:'.htmlspecialchars($a);<br />echo '<br>a1:';<br />$a1 = eregi_replace('(^[_.][:alnum:]-]+@([[:alnum:]][[:alnum:]-]*.)+[[:alpha:]]{2,3}$)',' <a href="mailto:\1">\1</a> ', $a) ;<br />echo htmlspecialchars($a1);<br />echo "<br>a1:$a1";<br />echo '<br>a2:';<br />$a2 = eregi_replace('([[:alnum:]]+://([[:alnum:]][[:alnum:]-]*\.)+[[:alpha:]]{2,3}([#\?/\\][^#\?/\\][:space:]][^[:space:]]*)?)',<br /> '<a href="\1" target="_blank">\1</a>', $a);<br />echo htmlspecialchars($a2);<br />echo "<br>a2:$a2";<br />// eregi('^[_.][:alnum:]-]+@([[:alnum:]][[:alnum:]-]*\.)+[[:alpha:]]{2,3}$',$a) or die("not a email");<br />?><br /><form name="f"><br /><input name="a" value="<?php echo $a; ?>"><br /><input type="submit" ><br /></form><br /></body></code></p>