Find an element in sorted rotated array

[funprogrammer]

I got this problem in an interview. I thought my solution was right but the interviewer said I was not using the sorted property of the array. I can see that I am using the standard binary search here but I am not able to understand why this does not provide the optimum solution.

I looked at this solution online - http://articles.leetcode.com/searching-element-in-rotated-array/
I am still not able to understand why my below solution is very different than what is mentioned in leet code. Any plain english explanation? Any pointers?

/*
Write a function to return if an element is part of sorted rotated array
*/ 
bool findInt(int arr[],int val, int size){
  cout<<"Inside findInt"<<endl;
  int start,end,mid;
  start=0;
  end=size-1;
  mid = (end-start)/2;

  while(start<=end){
    cout<<"start:"<<start<<",mid:"<<mid<<",end:"<<end<<endl;  
    if(arr[mid]==val) return true;
    if(val>=arr[start] && val<arr[mid]){
      end=mid-1;
      mid = start+((end-start)/2);
    }
    else{
      start=mid+1;
      mid = start+((end-start)/2);
    }
  }
  return false;
}

[ne555]

if(val>=arr[start] && val<arr[mid])
Because of the rotated property, `val' may be greater than `arr[start]' and `arr[mid]'.
In that case, the condition will fail and you would end searching in the wrong portion of the array.

[funprogrammer]

oh, got it now, thanks!