Other One-Argument Output Stream Manipulators

 

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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.

// 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;  
}  

Custom Manipulators with Arguments

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