In the example old URL you showed, the query string was just digits, not “t=” digits. Make sure you’re clear about what kind of query string you’re trying to match.
If this rewrite is in an htaccess file, which I suspect is the case, then you need to remove the leading slash from the pattern.
Ahh, yes. The original query string is retained unless you define a new one in the substitution URL, which is as simple as just adding a question mark.
its now working like a charm with both of u and here is the final code for who want
RewriteEngine on
RewriteCond %{QUERY_STRING} ([0-9]+)$
RewriteRule ^zaman/vb/showthread.php$ /smf/index.php/topic=%1? [R=301,L]
this code for who changing from vbulliten 4 to smf 2. offcourse u will not save all ur links but it help for the main posts
thank u for mr jeff and mr dklynn for their help
and thanks for all