关于Basic程序解释器及编译原理的简单化(1)--词法分析和代数式求值

关于Basic程序解释器及编译原理的简单化(1)--词法分析和代数式求值(4)         case NUMBER:
            *result = atoi(token);
            get_token();
            return;
        default:
            serror(0);
    }
}

/* perform the specified arithmetic */
void arith(char o,int *r,int *h)
{
    register int t,ex;
   
    switch (o)  {
        case '-':
            *r = *r-*h;
            break;
        case '+':
            *r = *r+*h;
            break;
        case '*':
            *r = *r**h;
            break;
        case '/':
            *r = (*r)/(*h);
            break;
        case '%':
            *r = (*r)%(*h);
            break;
        case '^':
            ex = *r;
            if (*h==0)  {
                *r = 1;