"Wiseguy" <noone@uber.usachoice.net> wrote in message
news:42955871$1_2@spool9-west.superfeed.net...
| consider the following:
|
| ostream_iterator<int> i(cout,"");
| cout << setw(3);
| copy(int_list.begin(),int_list.end(),i);
|
| the problem is that the field width restriction is only active for the first
| element of int_list. after the first element is copied to cout the stream
| setw(3) no longer has any affect.
|
| why? and how to use stream_iterators that don't modify the state of setw()?
|
|
| ostream iterators are of no use to me unless they can be used to
| enforce more complicated text formatting than the
| ostream_iterator(ostream&,string) constructor provides for.
If you only want a fixed width for each element, then you can
easily set the width of the string:
std::ostream_iterator<int> i( std::cout, " " );
Better yet, you might obtain it dynamically:
std::string Width( 4, ' ' );
std::ostream_iterator<int> i( std::cout, Width.c_str() );
Even better yet, what about using a function object ?:
# include <iostream>
# include <iomanip>
# include <ostream>
# include <list>
# include <algorithm>
inline void SpecialFormat( int n )
{
switch( n )
{
case 1 :
case 2 :
case 5 : std::cout << std::setw( 1 ) << n;
break;
case 10 : std::cout << std::setw( 5 ) << n;
break;
case 20 : std::cout << std::setw( 10 ) << n
<< std::setw( 3 )
<< std::setfill( '.' );
break;
case 30 : std::cout << std::setw( 15 ) << n;
break;
default:
std::cout << std::setw( 2 ) << std::left << n;
break;
}
}
int main()
{
std::list<int> int_list;
int_list.push_back( 10 );
int_list.push_back( 20 );
int_list.push_back( 30 );
std::for_each( int_list.begin(), int_list.end(), SpecialFormat );
return 0;
}
There are other possibilities too.
Hope this help's.
Cheers,
Chris Val
