char, pointer, cast and string questions

Question

/*1*/ const char *const letter = 'A';

/*2*/ const char *const letter = "Stack Overflow";

Why is 1 invalid but 2 valid?

letter is a pointer that needs to be assigned an address. Are quoted strings addresses? I'm assuming this is why #2 is valid and that single quoted strings are not considered addresses?

Also, what is the difference between these two casting types?:

static_cast<> and ().

And lastly, if var is a char variable, why does cout << &var << come out garbled? Why must I cast it to void*?

Thanks you for your patience with beginner questions.

Answer 1

Because 'A' is not a pointer, it's a char, 65 or 41₁₆ if the underlying character set is ASCII.

"Stack", on the other hand, is string, basically the character array {'S', 't', 'a', 'c', 'k', '\0'}, which degrades to a pointer to its first character.

Your "difference between static_cast and ()" has been answered here, far better than I could.

The reason why you get rubbish with a char var = 'x'; cout << &var ... is because &var is a char * which means it's being treated as a string - in that case, cout outputs characters up to the final nul character \0 which isn't there, or is there beyond the character. The following code shows this:

#include <iostream>
int main() {
    //int q1 = 0;
    char xx = 'x';
    //int q2 = 0;
    std::cout << &xx << std::endl;
    return 0;
}

outputting:

x~Í"

When you uncomment the q lines, it works, because it's putting zeros around the character, outputting x on its own). Keep in mind this is not kosher C, it's only working because of the way my stack is organised. Don't use this is real code.