Unhandled Exception / Access Violation

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I'm getting these errors on a mySQL database hat is connected to the interent. Maybe the connection is timing out? Or it's in the code. Here are the Errors.

This is the error that pops up in a message box.

Unhandled exception at 0x57088ce4 in lsniff.exe: 0xC0000005: Access violation reading location 0x00000000

This is under the call stack when the app breaks

>russ.exe!main(int _argc=1, char * * _argv=0x00251bf8) 
Line 224 + 0x9 bytes C++ russ.exe!__tmainCRTStartup() 
Line 278 + 0x19 bytes C russ.exe!mainCRTStartup() 
Line 189 C –

And this is next to the line in the code....

C++

res_set 0x00000000 {row_count=??? fields=??? data=??? ...}.

Here is the code.

C++

(mysql_real_connect(conn,"urlock.db.9873143.hostedresource.com"
,"Dk","Ad66","Dk",0,NULL,0) !=0);


char queryString[1024];
sprintf(queryString, "SELECT COUNT(*) FROM tblURLIP WHERE IP = '%s'
 AND IPStatus = '1' AND IPType = '3' AND IPMax ='0'", ipSrc == 0 ? "0" : ipSrc); 
mysql_query(conn, queryString);
my_ulonglong i = 0;
res_set = mysql_store_result(conn);
my_ulonglong numrows = mysql_num_rows(res_set);
LEGIT = mysql_fetch_row(res_set);

Posted 4-Oct-11 12:48pm

Member 7766180

Updated 4-Oct-11 16:18pm

walterhevedeich

v2

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Chuck O'Toole · Accepted Answer · 2011-10-04T13:44:00

Solution 1

10 seconds with Google / Bing revealed: http://dev.mysql.com/doc/refman/5.0/en/mysql-store-result.html[^] which tells you that mysql_store_result() can return a NULL if an error occurred. It returned NULL, you tried to use a null result ---> BOOM.

That page also tells you where to look to see what the error was.

Posted 4-Oct-11 13:44pm

Chuck O'Toole

Comments

Member 7766180 4-Oct-11 20:32pm

It was my understanding that if Count() found no records it would return a 0. However;ifit's returning an error, I guess that is a different story. Is there a way to make it return 0 on error as well? Thank you.

Chuck O'Toole 4-Oct-11 20:41pm

Just because something returns a zero if there are no records, that does not absolve you from handling error conditions. The documentation clearly says that it will return a NULL on error. mysql_error() and/or mysql_errno() will tell you the reason. Write code to call those routines when you get the NULL and find out what error you are receiving. We could sit here all day and GUESS but you should go straight to authoritive source, the defined mysql API.

thepenguinmaster 7-Dec-11 17:01pm

You know.. I hate when someone responds telling the person who asked how easy it would have been to just Google it. I Googled it, and got to this posting... I support the member for posting here.

Chuck O'Toole 7-Dec-11 20:23pm

you know, I hate it when someone posts something without having any context first. Like the fact that the original poster has a long history of just dumping things into these forums without doing any research for themselves. At some point, you just have to tell them to lookup things themselves first. Learn how to fish. Of course, the "go google this" also included the relevant link for the answer. Thanks for playing.