这个程序为什么输入字母或字符会进入死循环?如何解决,最好说明一下.是否能简化程序,谢谢!!!
程序如下:
#include "math.h"
#include "stdlib.h"
main()
{
    int guess,answer[4],i,j,proper,times=0,k;
    randomize();
    for(i=0;i<4;i++)
    {
        answer[i]=rand()%10;
        for(j=0;j<i;j++)
        if(answer[j]==answer[i]) { answer[i]=rand()%10; j=-1; }
    }
    printf("Please Guess:\n");
    while(proper!=4)
    {
        proper=0;
        printf("%d: ",++times);
        scanf("%d",&guess);
        while(guess<-1 || guess>9999)
        {
            printf("Input error......\nPlease reenter guess:\n");
            scanf("%d",&guess);
        }
        for(j=3;j>=0;j--)
        {
            for(i=0;i<4;i++)
              if(answer[i]==(int)(guess/pow(10,j)))
                if(i+j==3) proper++;
            guess=guess-(int)(guess/pow(10,j))*pow(10,j);
        }
        if(proper==4) printf("Very Good!!\n\nThe number is:");
          else printf("         %d correct\n",proper);
      }
    for(i=0;i<4;i++)
      printf("%d",answer[i]);
    getch();
}

还有一个问题！
屏满换屏时，背景颜色为什么也变了。