超载<<运营商ostream

Question

为什么下面的行不起作用？

#include <iostream>

std::ostream& operator <<( std::ostream& os, const char *c)
{
    os << c; // why does this line doesn't work?
    return os;
}

int main()
{
    const char *c = "Hi";
    std::cout << c;
}

Answer 1

问题是 std::ostream&运算符 <<( std::ostream& os, const char *c) 已在 iostream 中重载。