折半查找（C语言）

#include <stdio.h>
int look_up(int a[],int n,int x)
{
int left=0,right=n-1,mid;
while(left<=right)
{
mid=(left+right)/2;
if(x==a[mid])
return mid+1; //加一后才是它的逻辑位序
else if(x<a[mid])
right=mid-1;
else
left=mid+1;
}
if(left>right)
return -1;
}
int main()
{
int a[100],n,x,i,result;
scanf("%d",&n);
for(i=0;i<n-1;i++)
scanf("%d,",&a[i]);
scanf("%d",&a[i]);
scanf("%d",&x);
result=look_up(a,n,x);
if(result>=0)
printf("%d\n",result);
else
printf(“Not found\n”);
}