小编use*_*352的帖子

在C++中,如何在块的中途重命名变量？引用和宏感觉不对.

以下是否有效？:

template<typename T> class C { C1<C2<T>> someMember; };

class someClass
{
public:
    int* ptr2Int;
};

Is this a valid class (yes it compiles)? Provided one assigns a value to ptr2Int before dereferencing it, is the class guaranteed to work as one would expect?

我怎样才能完成以下建议？:

template<typename T>
class Base{...};
...
class Derived : public Base<int>{...};

我收到一个g ++错误(对'SomeClass :: SomeClass(int)'和'SomeClass ::〜SomeClass'的未定义引用),其中包含以下内容:

/*
 * SomeClass.h
 *
 */

#ifndef SOMECLASS_H_
#define SOMECLASS_H_

class SomeClass
{

public:
    SomeClass();
    SomeClass(int someInt);
    ~SomeClass();
};

#endif /* SOMECLASS_H_ */


/*
 * SomeClass.cpp
 *
 */

#include "SomeClass.h"

SomeClass::SomeClass()
{
}

SomeClass::SomeClass(int someInt)
{
}

SomeClass::~SomeClass()
{
}

/*
 * main.cpp
 *
 */

#include "SomeClass.h"

int main()
{

    SomeClass::SomeClass someObject(1);

    return 0;
}

应该SomeClass*initialEl = new SomeClass [5]; 必须编译,假设SomeClass没有非公开声明的默认构造函数？考虑:

/*
 * SomeClass.h
 *
 */

#ifndef SOMECLASS_H_
#define SOMECLASS_H_

class SomeClass
{

public:
    SomeClass(int){}
    ~SomeClass(){}
};

#endif /* SOMECLASS_H_ */


/*
 * main.cpp
 *
 */

#include "SomeClass.h"

int main()
{
    SomeClass* initialEl = new SomeClass[5];

    delete[] initialEl;

    return 0;
}

以下程序使用g ++编译,但在运行时崩溃:

class someClass
{
public:
    int const mem;
    someClass(int arg):mem(arg){}
};

int main()
{
    int arg = 0;
    someClass ob(arg);

    float* sample;
    *sample = (float)1;

    return 0;
}

以下程序不会崩溃:

int main()
{

    float* sample;
    *sample = (float)1;

    return 0;
}