求改错 pow 函数问题？

#include<iostream>
#include<math>
using namespace std;
int main()
{
    int answer[4]={1,3,5,2},guess,a,d,times=0,i,j;
    cout<<"Please guess"<<endl;
    while(a!=4)
    {
      int a=0,b=0;
      times++;
      cout<<"The guess numbers is:"<<times<<endl;
      scanf("%d",&guess);
      for(i=3;i<-1;i--)
      for(j=0;j<4;j++)
      {
      if((int)(guess/pow10(i))=answer[j]);
      if(i+j==3)
      a=a+1;
      else
      b=b+1;
      }
      guess=guess-(int)(guess/pow10(i))*pow10(i);
   
      printf("%da%db\n",a,b);}
      system("pause");
      return 0;
}