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char** argv is the same as char* argv[] because in the second case "the name of the array is a pointer to the first element in the array".
The first element of the array, argv[0] , is a pointer to the character array that contains the program name or invocation name of the program that is being run from the command line. argv[1] indicates the first argument passed to the program, argv[2] the second argument, and so on.
One usually uses pointer arithmetic when they want to get a pointer again. To get a pointer while using an array index: you are 1) calculating the pointer offset, then 2) getting the value at that memory location, then 3) you have to use & to get the address again.
From clang-tidy - cppcoreguidelines-pro-bounds-pointer-arithmetic:
Pointers should only refer to single objects, and pointer arithmetic is fragile and easy to get wrong.
span<T>is a bounds-checked, safe type for accessing arrays of data.
So yes:
Is there an alternative way to use the values of argv without using pointer arithmetic? Isn't accessing a char** by any sensible method going to have to use pointer arithmetic?
You're entirely correct. However, the guideline is about hiding that pointer arithmetic, letting a helper class do bounds checks before performing the arithmetic. You can construct a span<char*> from argv and argc. E.g. in C++20 you would write:
auto args = std::span(argv, size_t(argc));
and then use args instead of argv.
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