From: Warren Young
Date: November 13 2006 11:26pm
Subject: Re: Exception of type std::length_error
List-Archive: http://lists.mysql.com/plusplus/6104
Message-Id: <4558FF43.2030203@etr-usa.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 8bit

Mathieu Pagé wrote:
> 
> <code>
> mysqlpp::Row row;
> mysqlpp::Row::size_type i;
> for (i = 0; row = res.at(i); ++i)
>   cout <<row.at(0) <<endl;
> </code>
> 
> however I get an length_error exception on "row = res.at(i)".

I think you're expecting Row::at() to return false (or, rather, an 
object that can be converted to false) when you walk off the end of the 
result set.  MySQL++ doesn't do that sort of thing, by design.  It 
signals errors with exceptions, just as you saw.

That is the fall-back behavior when you turn off exceptions, however. 
Read the user manual for details.

You might also look at examples/simple3.cpp.  It operates in a way very 
similar to what you're doing, without needing special treatment.  It 
does that by using a different type of query than you are using.