6-9 统计个位数字

int Count_Digit ( const int N, const int D ){
  int n;
  if(N<0) 
  n=-N;
  else n=N;
  
  if(N==0&&D==0)
  return 1;
  
  int count=0;
  while(n){
    if(n%10==D)
      count++;
    n/=10;
  }
  return count;
}