打印较大的字符串 C++ 时出现问题

Question

我写了一个 class 用于跟踪错误并在必要时打印出错误消息。现在我运行它与测试人员对抗，以确定它是否可以正确检测错误并打印消息，但我在打印很长的字符串时遇到了问题。该代码在打印诸如 "Short Message" 之类的小字符串时工作正常，但在针对诸如 "Short Message" 之类的大字符串进行测试时 "Some error message that is really long long long long long long long long" “长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长长” 它失败了，我不确定我做错了什么。这是我的代码：

页眉

#ifndef SICT_ERRORMESSAGE_H__
#define SICT_ERRORMESSAGE_H__
#include <iostream>

namespace sict {
class ErrorMessage {
  char* message_;
public:
  ErrorMessage();
  ErrorMessage(const char* errorMessage);
  ErrorMessage& operator=(const ErrorMessage& em) = delete;
  ErrorMessage& operator=(const char* errorMessage);
  virtual ~ErrorMessage();
  void clear();
  bool isClear()const;
  void message(const char* value);
  const char* message() const;
  std::ostream& write(std::ostream& ostr)const;
};
  std::ostream& operator<<(std::ostream& os, const ErrorMessage& err);
}
#endif

CPP

#define CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstring>
#include "ErrorMessage.h"
namespace sict{

ErrorMessage::ErrorMessage() {
  message_ = nullptr;
}

ErrorMessage::ErrorMessage(const char* errorMessage) {
  message_ = nullptr;
  message(errorMessage);
}

ErrorMessage& ErrorMessage::operator=(const char* errorMessage) {
  clear();
  message();
  return *this;
}

ErrorMessage::~ErrorMessage() {
  delete [] message_;
}

void ErrorMessage::clear() {
  delete [] message_;
  message_ = nullptr;
}

 bool ErrorMessage::isClear() const {
  if(message_ == nullptr) {
    return true;
  }
  else {
    return false;
  }
}
void ErrorMessage::message(const char* value) {
  delete [] message_;
  message_ = new char[strlen(value) + 1];
  strcpy(message_, value);
  }

const char* ErrorMessage::message() const {
  return message_;
}

std::ostream& ErrorMessage::write(std::ostream& ostr)const {
if (!isClear()) {
  ostr << message_;
}
return ostr;
}

std::ostream& operator<<(std::ostream& os, const ErrorMessage& err) {
  return err.write(os);
}
}

主要

#include <iostream>
#include "ErrorMessage.h"
using namespace std;
using namespace sict;
int main() {
   ErrorMessage T("Testing Error Message");
   ErrorMessage e;
   cout << T << endl << e << endl << "isClear(): " << (e.isClear() ? "Passed!" : "failed!") << endl;
   cout << "===========|\r";
   for (int i = 0; i < 10000000; i++) {
      if (i % 1000000 == 0) {
         cout << "*";
         cout.flush();
  }
      e = "Some error message that is really long long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long"
     " long  long  long  long  long  long  long  long  long  long  long  long  long";
   }
   cout << '*' << endl;
   cout << e << endl << "isClear(): " << (e.isClear() ? "Failed!" : "Passed!") << endl;
   e.message("Short Message");
   cout << e << endl << e.message() << endl << "isClear(): " << (e.isClear() ? "Failed!" : "Passed!") << endl;
   e.clear();
   cout << e << endl << "isClear(): " << (e.isClear() ? "Passed!" : "Failed!") << endl;
   return 0;
}

Answer 1

您的赋值运算符有误：

ErrorMessage& ErrorMessage::operator=(const char* errorMessage) {
  clear();
  message();    // <-- Here!
  return *this;
}

我想你是想写 message(errorMessage)，它设置存储的错误消息，而不是 message()，它 returns 存储的错误消息。

尝试改变它，看看是否能解决问题。

打印较大的字符串 C++ 时出现问题

Trouble Printing Larger Character Strings C++

c++

string

char

ostream