I was mainly referring to function arguments. Any function that takes a pointer type has to have null checks at the beginning, since any of the pointer arguments may be null.
"has to" is a bit strong. The standard assumption is that pointer arguments should be set (or the function is documented otherwise), and the responsibility is left with the caller. It just bubbles out from there.
Yes, this is the way things have been done since 1965. It sounds simple enough, but as it turns out, in complex systems, this is a common cause of defects.
Programmers forget to check things all the time. Assumptions made in different areas of the code, by different programmers, at different times, do not always hold.
Fortunately, computers are good at remembering to check things. We just need to allow them to do so.
