#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int main()
{
int str[15]={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
printf("%d \n",erfen(str,15,7));
return 0;
}
int erfen(int str[],int len,int key)
{
int low=0;
int high=len-1;
int mid;
while(low<=high)
{
//mid=(low+high)/2;
mid=low+(high-low)/2;
if(key==str[mid])
return mid;
else if(key>str[mid])
low=mid+1;
else
high=mid-1;
}
return -1;
}