/* ---------------------------------------------------------------------  
// Figure 7.26:  Computing resistance.
// --------------------------------------------------------------------- 
*/
#include <stdio.h>                                                 

void main( void )                                                              
{   
    int r1, r2;         /* integer input variables for two resistances  */ 
    double r1d, r2d;    /* double variables for two resistances  */  
    double r_eq;        /* equivalent resistance of r1 and r2 in parallel */ 

    printf( "\n Enter integer value of resistances #1 and #2 (ohms):   " );   
    scanf( "%i%i", &r1, &r2 );
    printf( "    r1 = %i    r2 = %i \n", r1, r2 );

    r_eq = (r1 * r2) / (r1 + r2);           /* Oops!  Integer division. */  
    printf( "\n    The truncated resistance value is %g\n", r_eq );

    r_eq = ((double)r1 * r2) / (r1 + r2);   /* Better, we cast first. */
    printf( "    We cast to double first and get %g\n", r_eq );

    r1d = r1;                               /* Coerce to type double... */ 
    r2d = r2;                               /* by copying into double variables */
    r_eq = (r1d * r2d) / (r1d + r2d);       /* and compute using doubles. */ 
    printf( "    The true value of equivalent resistance is %g\n\n", r_eq );
}