How to pass a string as default argument in C++

Question

How can I properly pass a const string, for example: "Hello" as a default parameter to a constructor without getting any warnings and errors? In other words how can I preserve memory for them before the function is called?

Answer 1

#include <iostream>

const char *defString = "Hello";
void foo(const char *str = defString) {
    std::cout << str;
}

int main() {
    foo();
    foo("Hello, world!\n");
}