连接const char*字符串

Question

我很困惑char *和const char *.在我的例子中,我不确定如何将它们组合在一起.我有几个const char *字符串,我想连接到最后一个const char *字符串.

struct MyException : public std::exception
{
  const char *source;
  int number;
  const char *cause;

  MyException(const char *s, int n)
      : source(s), number(n) {}
  MyException(const char *s, const char *c)
      : source(s), number(0), cause(c) {}

  const char *what() const throw()
  {
    if (number != 0) {
      char buffer[1024];
      // why does this not work?
      cause = strerror_r(number, buffer, 1024);
    }

    // how to concatenate the strings?
    return source + ": " + cause;
  }
};

Answer 1

您可以存储一个std::string并仍然const char *从您的函数返回一个.

struct MyException : public std::exception
{
private:
  std::string message;  

public:    
  MyException(const char *s, int n) {
    char buffer[1024];
    strerror_r(n, buffer, 1024);
    message.reserve(strlen(s) + 2 + strlen(buffer));
    message = s;
    message += ": ";
    message += buffer;
  }

  MyException(const char *s, const char *c) {
    message.reserve(strlen(s) + 2 + strlen(c));
    message = s;
    message += ": ";
    message += c;
  }

  const char *what() const throw()
  {
    return message.c_str();
  }
};