Chapter 14, Problem 14.2E

(Variable-Length Argument List: Calculating Products) Write a program that calculates the product of a series of integers that are passed to function product using a variable-length argument list. Test your function with several calls, each with a different number of arguments.

Program Plan Intro

Program Plan:

This header file <stdarg.h>is used for object ap of type va_list is used by macros va_startva_arg and va_end to process the variable-length argument list of function product.

product( int x, ) :This function definition product is using a variable length argument list and calculate the product of a series of integers.

Printf (): used to print the data onto output screen.

Variables i, j, l, m, and n are of integer type which are passed as argument to function.

Total variable of integer type is used to store product of integer value.

Program Description: Purpose of the program is to calculates the series of integers that are passed to function product with several calls, by using a variable length list of arguments list and display result.

Explanation of Solution

Program: Following is Cprogram that calculates the series of integers that are passed to function product with several calls, by using a variable length list of arguments list and display result.

#include<stdio.h>//header file
#include<stdarg.h>///header-file for variable-length argument lists 
//Function prototype  
int product( int x, ... );
//Start of main  
intmain( void ) 
{
//Initialize the integers 
inti = 5;
int j = 4;
int k = 3;
int l = 2;
int m = 1;
//display user the values of integers
printf( "%s%d\n%s%d\n%s%d\n%s%d\n%s%d\n","i = ",
i, "j = ", j,"k = ", k,"l = ", l, "m = ", m );
//display the result of product using the function call to different series of integers 
printf( "%s%d\n%s%d\n%s%d\n%s%d\n",
"The Product of i and j is: ", product( 2,i,j ),
"The Product of i, j and k is: ",product(3,i,j,k ),
"The Product of i, j, k and 1 is: ", product(4,i,j,k,l ),
"The Product of i, j, k, 1, and m is: ",product(5,i,j,k,l,m) );
//terminate program succesfully
return0;

}//End of main  

//function product in which product of integers is passed as arguments
int product( int x, ... ) 
{
//Declare and initialize variable total
int total = 1;
//variable to counter loop
intz;

//Stores information needed by va_start and va_end. 

/*initialize variable Length argument List*/
va_listarg;

//Stores information needed by va_start. 

/*invoke the macros to access the arguments*/
va_start( arg, x );

//Process is running for variable length argument list. 

/*evaluate the total using for loop*/
for( z = 1; z <= x ; z++ ) 
    { 
        total *= va_arg( arg, int);
    }/*end of for loop*/


//Clean up variable-length argument list. 

/*Perform the housekeeping termination*/
va_end( arg);

/*return the arguments of product*/
returntotal;

}/*end of function Product*/

Explanation:

• Use header file notation for variable-length list of arguments.
• Read different series of integers in function call.
• Assign the value of total equals to 1 and use the argument list including va_list of variable list, next initialize va_start ( ) to invoke the macros so as to access the arguments in function definition.
• Loop for to evaluate the value of product.
• Display the product of a series of integers.

Sample Output: