Debugging method after Sphinx API call error

When we are using Coreseek or simple sphinx, if we call the API in the program, the function returns false, how do we debug in this case?
Such as:

The code is as follows	Copy Code
$res = $cl->query ($searchkey, ' myindex '); Var_dump ($res);d ie;

If Qquery error, then $res will only return false, and will not return the specific error message, in which case we can use
GetLastError method to get the last specific error message!!

code is as follows	copy code
Var_dump ($ Cl->getlasterror ());