basic_stringstream rounds large numbers?!

[MattWoberts]

Hi,

I'm a bit of a newbie in VC C++, any help would be great:

I am using a basic_stringstream to generate a SQL statement to execute on a database, and into this stream I input a double, like this:

sBuffer << dValue;

This is OK, but if dValue is a larger number than 1000000, then the number is rounded off, e.g. 1000001 becomes 1000000, and 1000007 becomes 1000010. Please help!!

 

[rjr9999]

A better understanding of decimal math will help, look here :

http://www2.hursley.ibm.com/decimal/

Rob
&quot;Programming is like art...It makes me feel like chopping my ear off.&quot;

Http://www.thisisrisk.com/

- Currently down

 

[MattWoberts]

I'm not sure that decimal match is an issue here (unless I've missed something) - if I have a string buffer, and use << to add something to the string (in this case the something refers to a double), then why should the string contain other than the value?

On closer inspection it appears that number > 1000000 are being represented exponentially, e.g. 10000049 actually appends to the string buffer as 1.00001e+7, hence the last 2 numbers are rounded and chopped off.

Am I missing something obvious?

 

[ETasse]

Force the stringstream to never use floating point using the manipulator classes:

#include <iomanip>
sBuffer << setw(15) << setiosflags(iso_base::fixed) << dValue;

 

[MattWoberts]

Excellent!

That works nicely, many thanks