Why is argv ended by a nullpointer?

Question

In the execve() man page it is said that argv is a list of string arguments which is ended by a null pointer. But what is the NP for? I mean, the number of arguments is stored in argc, so what's the point of the null pointer?

Answer 1

The count for argc is calculated by looking for this NULL.

Answer 2

execve does not take argc as a parameter, it manually counts the arguments you give as argv to determine argc itself.

This is for compatibility with execl which takes a variable number of arguments instead of an argv array.