Using variable-length argument lists. - C++ Function

C++ examples for Function:Function Parameter

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Description

Using variable-length argument lists.

Demo Code

#include <iostream> 
#include <iomanip> 
#include <cstdarg> 
using namespace std; 

double average( int, ... ); 

int main() /*from w  w  w .  j a v a 2 s  .  co  m*/
{ 
   double double1 = 37.5; 
   double double2 = 22.5; 
   double double3 = 1.7; 
   double double4 = 10.2; 

   cout << fixed << setprecision( 1 ) << "double1 = " 
         << double1 << "\ndouble2 = " << double2 << "\ndouble3 = " 
         << double3 << "\ndouble4 = " << double4 << endl 
         << setprecision( 3 ) 
         << "\nThe average of double1 and double2 is " 
         << average( 2, double1, double2 ) 
         << "\nThe average of double1, double2, and double3 is " 
         << average( 3, double1, double2, double3 ) 
         << "\nThe average of double1, double2, double3" 
         << " and double4 is " 
         << average( 4, double1, double2, double3, double4 ) 
         << endl; 
} 

// calculate average 
double average( int count, ... ) 
{ 
   double total = 0; 
   va_list list;  // for storing information needed by va_start 

   va_start( list, count ); 

   // process variable-length argument list 
    for ( int i = 1; i <= count; i++ ) 
       total += va_arg( list, double ); 

   va_end( list ); // end the va_start 
    return total / count; 
}

Result


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