Why it is showing -1?

Question

https://code.sololearn.com/cp5OefNl9W8g/?ref=app

Answer 1

Change the conditions

if(arr[mid]>t)
end=mid-1;

else
if(arr[mid]<t)
start=mid+1;

Answer 2

if you search start..mid
[1,3| ] numbers
3<5 so you have to search start=mid+1
[ |5,6]
but you do end=mid-1 instead
[1| ]
next start=0 and end=-1 and loop ends unsucess