C ++循环遍历对象的地址
C++ Cycle through the addresses of an object
对象(不是动态的)是内存中的数据块。
有没有办法循环打印对象中的每一项?
我尝试用 'this' 来做,但我总是出错。
#include "stdafx.h"
#include <iostream>
#include "TestProject.h"
using namespace std;
class myclass {
int someint = 10;
double somedouble = 80000;
int somearray[5] = {0, 1, 2, 3, 4};
public:
void somefunction();
};
void myclass::somefunction() {
cout << "\n test \n" << this;
myclass *somepointer;
somepointer = this;
somepointer += 1;
cout << "\n test2 \n" << *somepointer;
//Error: no opperator '<<' matches these operands
}
int main() {
myclass myobject;
myobject.somefunction();
return 0;
}
我猜错误是因为类型不匹配。但我真的想不出解决办法。是否有动态类型,或者我必须以某种方式测试类型?
必须添加全局好友std::ostream operator <<
才能显示对象内容
#include "stdafx.h"
#include <iostream>
using namespace std;
class myclass {
int someint;
double somedouble;
int somearray[5];
public:
myclass()
{
someint = 10;
somedouble = 80000;
somearray[0] = 0;
somearray[1] = 1;
somearray[2] = 2;
somearray[3] = 3;
somearray[4] = 4;
}
void somefunction();
friend std::ostream& operator << (std::ostream& lhs, const myclass& rhs);
};
std::ostream& operator << (std::ostream& lhs, const myclass& rhs)
{
lhs << "someint: " << rhs.someint << std::endl
<< "somedouble: " << rhs.somedouble << std::endl
<< "somearray: { ";
for (int iIndex = 0; iIndex < 5; iIndex++)
{
if (iIndex == 4)
lhs << rhs.somearray[iIndex] << " }" << std::endl;
else
lhs << rhs.somearray[iIndex] << ", ";
}
return lhs;
}
void myclass::somefunction() {
cout << "\n test \n" << this;
myclass *somepointer;
somepointer = this;
somepointer += 1; // wrong pointer to object with `object + sizeof(object)` address,
// data probably has been corrupted
cout << "\n test2 \n" << *somepointer; // displaying objects content
}
int main() {
myclass myobject;
myobject.somefunction();
return 0;
}
因为你想使用它的指针移动到对象成员我post另一个程序
#include "stdafx.h"
#include <iostream>
using namespace std;
#pragma pack (push, 1) // force data alignment to 1 byte
class myclass {
int someint;
double somedouble;
int somearray[5];
public:
myclass()
{
someint = 10;
somedouble = 80000;
somearray[0] = 0;
somearray[1] = 1;
somearray[2] = 2;
somearray[3] = 3;
somearray[4] = 4;
}
void somefunction();
friend std::ostream& operator << (std::ostream& lhs, const myclass& rhs);
};
#pragma pack (pop) // restore data alignment
std::ostream& operator << (std::ostream& lhs, const myclass& rhs)
{
lhs << "someint: " << rhs.someint << std::endl
<< "somedouble: " << rhs.somedouble << std::endl
<< "somearray: { ";
for (int iIndex = 0; iIndex < 5; iIndex++)
{
if (iIndex == 4)
lhs << rhs.somearray[iIndex] << " }" << std::endl;
else
lhs << rhs.somearray[iIndex] << ", ";
}
return lhs;
}
void myclass::somefunction() {
int* pSomeInt = (int*)this; // get someint address
double *pSomeDouble = (double*)(pSomeInt + 1); // get somedouble address
int* pSomeArray = (int*)(pSomeDouble + 1); // get somearray address
std::cout << "someint: " << *pSomeInt << std::endl
<< "somedouble: " << *pSomeDouble << std::endl
<< "somearray: { ";
for (int iIndex = 0; iIndex < 5; iIndex++)
{
if (iIndex == 4)
std::cout << pSomeArray[iIndex] << " }" << std::endl;
else
std::cout << pSomeArray[iIndex] << ", ";
}
}
int main() {
myclass myobject;
myobject.somefunction();
return 0;
}
C++ 在设计上没有反射功能。这意味着在运行时没有通用的、类型无关的方法来访问类型元数据(例如,成员列表 if a class 及其类型)。所以你想做的事情(如果我理解正确的话)不能在 C++ 中完成。
此外,我不确定您所说的 "objects (that are not dynamic)" 是什么意思。所有对象都是内存中的数据块,无论它们是否动态分配。
对象(不是动态的)是内存中的数据块。
有没有办法循环打印对象中的每一项?
我尝试用 'this' 来做,但我总是出错。
#include "stdafx.h"
#include <iostream>
#include "TestProject.h"
using namespace std;
class myclass {
int someint = 10;
double somedouble = 80000;
int somearray[5] = {0, 1, 2, 3, 4};
public:
void somefunction();
};
void myclass::somefunction() {
cout << "\n test \n" << this;
myclass *somepointer;
somepointer = this;
somepointer += 1;
cout << "\n test2 \n" << *somepointer;
//Error: no opperator '<<' matches these operands
}
int main() {
myclass myobject;
myobject.somefunction();
return 0;
}
我猜错误是因为类型不匹配。但我真的想不出解决办法。是否有动态类型,或者我必须以某种方式测试类型?
必须添加全局好友std::ostream operator <<
才能显示对象内容
#include "stdafx.h"
#include <iostream>
using namespace std;
class myclass {
int someint;
double somedouble;
int somearray[5];
public:
myclass()
{
someint = 10;
somedouble = 80000;
somearray[0] = 0;
somearray[1] = 1;
somearray[2] = 2;
somearray[3] = 3;
somearray[4] = 4;
}
void somefunction();
friend std::ostream& operator << (std::ostream& lhs, const myclass& rhs);
};
std::ostream& operator << (std::ostream& lhs, const myclass& rhs)
{
lhs << "someint: " << rhs.someint << std::endl
<< "somedouble: " << rhs.somedouble << std::endl
<< "somearray: { ";
for (int iIndex = 0; iIndex < 5; iIndex++)
{
if (iIndex == 4)
lhs << rhs.somearray[iIndex] << " }" << std::endl;
else
lhs << rhs.somearray[iIndex] << ", ";
}
return lhs;
}
void myclass::somefunction() {
cout << "\n test \n" << this;
myclass *somepointer;
somepointer = this;
somepointer += 1; // wrong pointer to object with `object + sizeof(object)` address,
// data probably has been corrupted
cout << "\n test2 \n" << *somepointer; // displaying objects content
}
int main() {
myclass myobject;
myobject.somefunction();
return 0;
}
因为你想使用它的指针移动到对象成员我post另一个程序
#include "stdafx.h"
#include <iostream>
using namespace std;
#pragma pack (push, 1) // force data alignment to 1 byte
class myclass {
int someint;
double somedouble;
int somearray[5];
public:
myclass()
{
someint = 10;
somedouble = 80000;
somearray[0] = 0;
somearray[1] = 1;
somearray[2] = 2;
somearray[3] = 3;
somearray[4] = 4;
}
void somefunction();
friend std::ostream& operator << (std::ostream& lhs, const myclass& rhs);
};
#pragma pack (pop) // restore data alignment
std::ostream& operator << (std::ostream& lhs, const myclass& rhs)
{
lhs << "someint: " << rhs.someint << std::endl
<< "somedouble: " << rhs.somedouble << std::endl
<< "somearray: { ";
for (int iIndex = 0; iIndex < 5; iIndex++)
{
if (iIndex == 4)
lhs << rhs.somearray[iIndex] << " }" << std::endl;
else
lhs << rhs.somearray[iIndex] << ", ";
}
return lhs;
}
void myclass::somefunction() {
int* pSomeInt = (int*)this; // get someint address
double *pSomeDouble = (double*)(pSomeInt + 1); // get somedouble address
int* pSomeArray = (int*)(pSomeDouble + 1); // get somearray address
std::cout << "someint: " << *pSomeInt << std::endl
<< "somedouble: " << *pSomeDouble << std::endl
<< "somearray: { ";
for (int iIndex = 0; iIndex < 5; iIndex++)
{
if (iIndex == 4)
std::cout << pSomeArray[iIndex] << " }" << std::endl;
else
std::cout << pSomeArray[iIndex] << ", ";
}
}
int main() {
myclass myobject;
myobject.somefunction();
return 0;
}
C++ 在设计上没有反射功能。这意味着在运行时没有通用的、类型无关的方法来访问类型元数据(例如,成员列表 if a class 及其类型)。所以你想做的事情(如果我理解正确的话)不能在 C++ 中完成。
此外,我不确定您所说的 "objects (that are not dynamic)" 是什么意思。所有对象都是内存中的数据块,无论它们是否动态分配。