Other One-Argument Output Stream Manipulators
The latest version of this topic can be found at Other One-Argument Output Stream Manipulators.
The following example uses a class money, which is a long type. The setpic manipulator attaches a formatting "picture" string to the class that can be used by the overloaded stream insertion operator of the class money. The picture string is stored as a static variable in the money class rather than as data member of a stream class, so you do not have to derive a new output stream class.
Example
// one_arg_output.cpp
// compile with: /GR /EHsc
#include <iostream>
#include <iomanip>
#include <string>
using namespace std;
typedef char* charp;
class money
{
private:
long value;
static char *szCurrentPic;
public:
money( long val ) { value = val; }
friend ostream& operator << ( ostream& os, money m ) {
// A more complete function would merge the picture
// with the value rather than simply appending it
os << m.value << '[' << money::szCurrentPic << ']';
return os;
}
static void setpic( char* szPic ) {
money::szCurrentPic = new char[strlen( szPic ) + 1];
strcpy_s( money::szCurrentPic, strlen( szPic ) + 1, szPic );
}
};
char *money::szCurrentPic; // Static pointer to picture
void fb( ios_base& os, char * somename )
{
money::setpic(somename);
/*
ostream *pos = dynamic_cast<ostream*>(&os);
if (pos)
{
for( int i=0; i < l; i++ )
(*pos) << ' ';
};
*/
}
_Smanip<charp>
__cdecl setpic(char * somename)
{
return (_Smanip<charp>(&fb, somename));
}
int main( )
{
money amt = (long)35235.22;
cout << setiosflags( ios::fixed );
cout << setpic( "###,###,###.##" ) << "amount = " << amt << endl;
}