C++ char*[] to char** conversion

Question

I have this simple code that compiles without errors/warnings:

void f(int&, char**&){}

int main(int argc, char* argv[])
{
    f(argc, argv);
    return          


        

Answer 1

Because despite appearances, the second argument to main has type char**. When used as the declaration of a function argument, a top level array is rewritten to a pointer, so char *[] is, in fact, char**. This only applies to function parameters, however.

A char*[] (as in your second case) can convert to a char**, but the results of the conversion (as with any conversion) is an rvalue, and cannot be used to initialize a non-const reference. Why do you want the reference? If it is to modify the pointer, modifying the char** argument to main is undefined behavior (formally, in C, at least—I've not checked if C++ is more liberal here). And of course, there's no way you can possibly modify the constant address of an array. And if you don't want to modify it, why use a reference?