c++ - 为我在 C++ 中创建的对象声明一个变量

Question

我是一名 Java 专家，我正在尝试使用 C++ 为一门课做作业。我无法将我创建的类型的变量声明为另一个类的属性。这是我的方法

  private:
    HeatingUnit heatingUnit;
    int tempToMaintain;

  public:
    BangBangControl(int tempToMaintain, bool isOn, int initialTemp){
      heatingUnit= new HeatingUnit(isOn, initialTemp);
      this -> tempToMaintain = tempToMaintain;
    }

我收到这个错误

BangBangControl.cpp: In constructor ‘BangBangControl::BangBangControl(int, bool, int)’:
BangBangControl.cpp:15: error: no match for ‘operator=’ in ‘((BangBangControl*)this)->BangBangControl::heatingUnit = (((HeatingUnit*)operator new(8u)), (<anonymous>->HeatingUnit::HeatingUnit(((int)isOn), initialTemp), <anonymous>))’
HeatingUnit.h:6: note: candidates are: HeatingUnit& HeatingUnit::operator=(const HeatingUnit&)
BangBangControl.cpp: In member function ‘int BangBangControl::main()’:
BangBangControl.cpp:37: error: no match for ‘operator<<’ in ‘std::operator<< [with _Traits = std::char_traits<char>](((std::basic_ostream<char, std::char_traits<char> >&)((std::basic_ostream<char, std::char_traits<char> >*)((std::basic_ostream<char, std::char_traits<char> >*)std::operator<< [with _Traits = std::char_traits<char>](((std::basic_ostream<char, std::char_traits<char> >&)(& std::cout)), ((const char*)"Temp to maintain is: ")))->std::basic_ostream<_CharT, _Traits>::operator<< [with _CharT = char, _Traits = std::char_traits<char>](bBC. BangBangControl::getTemp()))), ((const char*)" Current temp is: ")) << bBC. BangBangControl::update()’
/usr/include/c++/4.2.1/ostream:112: note: candidates are: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>& (*)(std::basic_ostream<_CharT, _Traits>&)) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/ostream:121: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ios<_CharT, _Traits>& (*)(std::basic_ios<_CharT, _Traits>&)) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/ostream:131: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::ios_base& (*)(std::ios_base&)) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/ostream:169: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/ostream:173: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/ostream:177: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(bool) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/bits/ostream.tcc:92: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short int) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/ostream:184: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short unsigned int) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/bits/ostream.tcc:106: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/ostream:195: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(unsigned int) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/ostream:204: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long long int) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/ostream:208: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long long unsigned int) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/ostream:213: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(double) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/ostream:217: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(float) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/ostream:225: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long double) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/ostream:229: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(const void*) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/include/c++/4.2.1/bits/ostream.tcc:120: note:                 std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_streambuf<_CharT, _Traits>*) [with _CharT = char, _Traits = std::char_traits<char>]

Answer 1

HeatingUnit heatingUnit;

应该是:

HeatingUnit *heatingUnit;
            ^^

我相信您的意图是创建一个类型为 HeatingUnit 的指针，因为您在构造函数中使用了 new。 new 用于将空闲存储上的内存分配给指针变量。

如果创建指针不是您的意图(我不确定，因为您是从没有指针的 Java 迁移过来的)，只需使用:

   HeatingUnit heatingUnit;

但不要在构造函数中使用 `new 分配内存。