程序代码：

#include <stdio.h>
#include <math.h>
#define S sum=sum
double change(char c[10])
{int t;

 double q,sum=0;

 for(t=0;t<10;t++)
{q=pow(16,9-t);

 switch(c[t])
  case 'a':S+10*q;break;
  case 'b':S+11*q;break;
  case 'c':S+12*q;break;
  case 'd':S+13*q;break;
  case 'e':S+14*q;break;
  case 'f':S+15*q;break;
  default:S+(c[t]-48)*q;}//What's wrong with my switch?
return sum;}