为什么我写的程序在turbo c下能运行，而在vc6.0上却不能运行啊，希望那位热心的朋友能提供一下解决问题，

就是这段代码，到vc中就运行不了，
#include <math.h>
#include <stdio.h>
void main(void)
{
    int answer[4]={1,3,5,2},guess,a,b,times=0,i,j;    //初始化被猜答案为1352
    printf("Please input the guess number:\n");
    while (a != 4)                                    //进入猜数字的循环
    {
        a = 0;
        b = 0;                                        //每次猜测之前设定A,B都为0
        times++;                                      //猜测次数加1
        printf("第%d次猜测",times);
        scanf("%d",&guess);                           //从键盘读取猜的四位数字
        for (i = 3;i > -1;i--)
        {
            for (j = 0;j< 4; j++)                     //进入猜测和正确答案比对循环
            {
                if ((int)(guess/pow10(i)) == answer[j])   //将每一位猜测数字比对  pow10（i）是去10的i次方
                {                                                            
                    if(i + j == 3)
                        a = a+1;      //如果位置相同，a就加1
                    else
                        b=b+1;       //如果位置不同，b就加1
                }
            }
            guess=guess-(int)(guess/pow10(i))*pow10(i);   //比对下一个猜测数字
        }
        printf("%d A %d B\n",a,b);                          //显示本次猜测的A，B正确性
    }
}