Code

 Header...
double max (double x1,double x2);

 int main(){
   ... 

»  double x1, x2, xmax;

»  printf("Please enter two real numbers\n");
»  scanf("%lg %lg", &x1, &x2);

»  xmax=max(x1, x2);

»  printf("The maximum of %g and %g is %g\n", x1, x2, xmax);

»  return 0;
}

// Return the maximum of two doubles
 double max(double x1,double x2){
   ... 

»  if (x1>x2) 
    return x1;

»  return x2;
}

Data