#include <stdio.h>#include <float.h> union ieee_double_extract{    struct {        unsigned int manl:32;        unsigned int manh:20;        unsigned int exp:11;        unsigned int sig:1;    } s;    double d;}; double scale(double d){    union ieee_double_extract x;     x.d = d;    x.d *= 1000;    return x.d;} void mul(double *p){    *p *= 2.0;} intmain(void){    double d = 4.0;    printf("%g\n", scale(42));    mul(&d);    printf("%g\n", d);    return 0;}