类构造函数在每个实例化的同一内存位置构建结构，但其他成员在自己的内存位置构建？

Question

我有一个类，在实例化时我会构建两个标准结构成员。我的实例化是独立的，并且每次我构建一个实例时都在它自己的内存空间中，就像名称成员一样，但是构造函数中构建的结构每次都被赋予相同的内存地址，从而覆盖先前的实例化结构？指针和结构在任何地方都是静态的，所以我不明白为什么会发生这种情况。如果有人能发现我的错误，请指出。

-------------signal.h--------------
prama once

struct GenParams
{
 float a;
 float b;
};


class signal {
public:
signal();
~signal();
std::string sigName;
GenParams* mGP;  //not static so every instance should have its own mGP I set to private as well but made no difference.
};
--------------------siganl.cpp------------------

#include signal.h

signal::signal()
{  
   GenParams GP; //every instance should have its own member GP at a unique mem location
    // but instead GP is created at the same mem location
   mGP = &GP;  // mGP points to the same mem location every time the constructor is called

   //fill struct with default values
   GP.a = 0.0;
   GP.b = 5.0;
}
signal::~signal()
{ }

--------------------interface.h--------------------
#include signal.h

class interface
{
public:
interface();
~interface();

std::string interName;
std::vector<signal*> sigList;
interface* iPtr;
unsigned int sigNum;

void newSignal();

--------------------------------interface.cpp----------------------

#include interface.h

interface::interface() : iPtr(this)
{  sigNum = 0;}

interface::~interface()
{
  for (auto i : sigList)
      delete i;
}

interface::newSignal()
{
   signal* s = new signal;
 //after this line returns the values are stored correctly in memory of struct

//during this line which does not reference the struct or the signal yet I see the structs
// memory get deallocated and go red as if something is writing to it and the values are gone
   std::string newSName = this->interName + "sig" std::to_string(sigNum + 1);

//Here some values go back into the struct but they are bogus vals
   s->sigName = newSName;

   sigList.push_back(s);
//after adding to the list the sig instance has a name correctly written by the line above
//and a pointer it it but the pointer to the struct member mGP all instances point to the 
//same memory location?? I don't understand how this is happening.
   sigNum++;
  
}

Answer 1

此构造函数调用未定义的行为

signal::signal()
{  
   GenParams GP; //every instance should have its own member GP at a unique mem location
    // but instead GP is created at the same mem location
   mGP = &GP;  // mGP points to the same mem location every time the constructor is called

   //fill struct with default values
   GP.a = 0.0;
   GP.b = 5.0;
}

因为数据成员mGP

mGP = &GP;

设置为GP具有自动存储方向的局部变量的地址

GenParams GP;

退出构造函数后将不再存在。

因此数据成员mGP将具有无效值。

您应该动态分配该类型的对象GenParams或拥有该类型的数据成员。

注意这一行

 std::string newSName = this->interName + "sig" std::to_string(sigNum + 1);

有一个错字。看来你的意思是

 std::string newSName = this->interName + "sig" + std::to_string(sigNum + 1);