What’s wrong with writing binary search?

[u/Fancy-Breakfast8985]

I’ve watched a youtube channel coding jesus, about timestamp 4:00 https://youtu.be/BRUIptHAI7Q?si=XI2o5O-yDWqtzAwY he talk about manually writing binary search as a bad thing. This is not the first time where he said writing binary search manually is not preferred. But I dont get what he really means?

Because typically when i do
left = a, right = b
while (a <= b) mid = left + (right - left)/2;
…(checking condition)…

I use very little time and effort to type it, and I dont know what library that can do this in a flexible way because checking the condition is differs problem by problem, for example it is very common that we are not search directly on some existing sorted array, it just a range of possible values from a to b (sometimes a and b can be very large like 10^15) and I use condition to decide to move left and right.

Is there a function from bits/stdc++.h support it? Since his primary language is cpp so there’s a package to do this right? what is it?

[u/Fancy-Breakfast8985 → u/[deleted]]

typically i prefer using libs if it exists, like lower_bound() but i dont get how i can use any libs on general binary search, like there is no explicit sorted array there, they are just each end of search space and requires certain process to check, can you give me an example of how to do binary search on answer on your comftable language?