ostringstream width

gecoool · 12-07-2005, 03:38 AM

Hello people ;-)

I wish to find out if there is a way to "keep" the width of an ostringstream after it was set with width() call. That is if I set the width to 2 (i.e) after first << operation, the width of the stream goes back to the default value.

ostringstream off;
off.width(2);
off.fill('0');

int k=3;

off<<3; //this one produces off.str()="03"
int j=2;
off<<j; //now i get "032"; //and i would like to get 0302, without repeted call to width and fill ... If this is possible, please advise me.

sirclif · 12-08-2005, 12:49 PM

I don't think so, i found this website with the following note:

NOTE -- With the exception of the field width, all format parameter settings are permanent. The field width parameter is reset after each use

sirclif · 12-08-2005, 12:53 PM

oh, but by the way, you can set the width in the ostring.

#include <iostream>
#include <iomanip>

ostringstream off;

off.fill('0');

off<<std::setw(2)<<3<<std::setw(2)<<2;

will set the width for both statements.
not the iomanip include, the std::setw() function is defined there.

gecoool · 12-09-2005, 02:02 AM

Thankz sirclif ;-)

The relevant answer for me is the first one: ironically the width property is the only one non-permanent

for the stream. What I intended was to avoid making the call of off.width() or another one (i.e. setw) every time. It is actually a piece of "critical" code ... in terms of speed. I dropped the idea of using streams and fell back to old char array ;-), which is fastest. Anyway I must thank you for your time.