```
#include<stdio.h>
int binary_search(int arr[], int size ,int element){
int low, mid, high;
low=0;
high=size-1;
//start of search
while(low<=high)
{
mid = (low + high)/2;
if(arr[mid] == element){
return mid;
}
if(arr[mid]<element){
low= mid+1;
}
else{
high = mid-1;
}
}
//end of search
return -1;
}
int main(){
int arr[20]={1,20,31,44,54,68,70,85};
int size= sizeof(arr)/sizeof(int);
int element=44;
int Si= binary_search(arr,size,element);
printf("Element was found at index: %d \n",Si);
return 0;
}
```

why does my code returns -1 everytime .

I tried changing arr[20] to arr[] in main function and it started working fine.

Can someone explain me the reason behind this?

### >Solution :

This line of code creates an integer array of length `20`

, with all the elements after `85`

being initialized to zeros.

```
int arr[20]={1,20,31,44,54,68,70,85};
```

The `sizeof`

operator gives the size, in bytes, of the integer array `arr`

of length 20, which causes the value of `size`

to be 20. This causes the binary search algorithm to fail, as it does not deal with arrays that are not sorted.