[C] Function - multiply argument use … to represent



#include

#include





/* this function will take the number of values to average

followed by all of the numbers to average */

double average ( int num, … )

{

va_list arguments;

double sum = 0;

int x = 0;



/* Initializing arguments to store all values after num */

va_start ( arguments, num );

/* Sum all the inputs; we still rely on the function caller to tell us how

* many there are */

for (x = 0; x < num; x++ )

{

sum += va_arg ( arguments, double );

}

va_end ( arguments ); // Cleans up the list



return sum / num;

}



int main()

{

/* this computes the average of 13.2, 22.3 and 4.5 (3 indicates the number of values to average) */

printf( “%f\n”, average ( 3, 12.2, 22.3, 4.5 ) );

/* here it computes the average of the 5 values 3.3, 2.2, 1.1, 5.5 and 3.3 */

printf( “%f\n”, average ( 5, 3.3, 2.2, 1.1, 5.5, 3.3 ) );

}





Reference

1. Lesson 17: Functions with Variable Argument Lists in C using va_list