如何做我自己的自定义运行时错误类？

Question

我正在尝试做一个简单的自定义runtime_error.我定义了这个类:

#include <string>
#include <stdexcept>


namespace utils{

 class FileNotFoundException: public std::runtime_error{
  public:
   FileNotFoundException():runtime_error("File not found"){}
   FileNotFoundException(std::string msg):runtime_error(msg.c_str()){}
 };

};

然后我抛出错误:

bool checkFileExistence( std::string fileName )
 {
  boost::filesystem::path full_path = boost::filesystem::system_complete(boost::filesystem::path(fileName));
  if (!boost::filesystem::exists(full_path))
  {
    char msg[500];
    _snprintf(msg,500,"File %s doesn't exist",fileName.c_str());
    throw new FileNotFoundException(msg);
  }
 }

我使用try/catch块

    try{
          checkFileExistence(fileName);
     }
   catch(utils::FileNotFoundException& fnfe)
        {
          std::cout << fnfe.what() << std::endl;
     }

运行时错误被正确抛出为FileNotFoundException,但是从未到达带有std :: cout的行,并且没有行被写入控制台.

欢迎所有想法.谢谢!

Answer 1

那是因为你扔了一个指针.只是做:throw FileNotFoundException(msg);.

每当你使用指针时,除非你把它放入容器/包装器中,否则你可能没有做正确的事情.

Answer 2

你写的throw new FileNotFoundException(msg),应该是'throw FileNotFoundException(msg)'.规则是逐个值,通过引用捕获.