求助啊，有关于折半查找的问题
# include <stdio.h># define N 15
int main ()
{
int i,number,top,bott,mid,loca,a[N],flag =1,sign;
char c;
printf("enter data :\n");
scanf("%d",&a[0]);
i =1;
while(i<N)
{
scanf("%d",&a[i]);
if (a[i]>=a[i-1])
i++;
else
printf("enter this data again:\n");
}
printf("\n");
for (i =0;i<N;i++)
printf("%5d",a[i]);
printf("\n");
while (flag)
{
printf("input number to look for:");
scanf("%d",&number);
sign =0;
top = 0;
bott = N-1;
if ((number<a[0] )|| (number>a[N-1]))
loca=-1;
while (!sign && top<=bott)
{
mid =(bott+top)/2;
if (number==a[mid])
{
loca= mid;
printf("has found %d,its position is %d\n",number,loca+1);
sign =1;
}
else if(number<a[mid])
bott =mid-1;
else
top = mid+1;
}
if( !sign || loca==-1)
printf("cannot find %d\n",number);
printf("continue or not(Y/N)");
scanf("%c",&c);
if(c=='N'||c=='n')
flag = 0;
}
return 0;
}
/*输出为：
enter data :
1
3
4
5
6
8
12
23
34
44
45
56
57
58
68
1 3 4 5 6 8 12 23 34 44 45 56 57 58 68
input number to look for:7
cannot find 7
continue or not(Y/N)input number to look for:n
cannot find 7
continue or not(Y/N)请按任意键继续. . .
其中while (!sign && top<=bott)中!sign为什么为0，这程序中的sign值变化不理解，求指点·····
