Append a char into std::stringstream in C++ is hard

main.cpp

#include <sstream>
#include <string>
#include <cstdio>

int main() {
  std::stringstream a;
  a << "0";  // const char *
  printf("%s\n", a.str().c_str());  // 0, expected

  std::stringstream b;
  b << std::string("0");  // std::string
  printf("%s\n", b.str().c_str());  // 0, expected, std::string seems duplicated

  std::stringstream c;
  c << '0'; // char
  printf("%s\n", c.str().c_str()); // 0, expected

  std::stringstream d;
  d << 0; // int
  printf("%s\n", d.str().c_str()); // 0, int is parsed literally, other than as ASCII code, we know but may ignore or misundertand

  std::stringstream e;
  e << 0x00; // int
  printf("%s\n", e.str().c_str()); // 0, hex is still int

  std::stringstream f;
  f << '\x00'; // char
  printf("%s\n", f.str().c_str()); // None, char(0) works

  std::stringstream g;
  g << char(0); // char
  printf("%s\n", g.str().c_str()); // None, more explicitly

  std::stringstream h;
  h << static_cast<char>(0); // char
  printf("%s\n", h.str().c_str()); // None, modern C++ version

  return 0;
}