指针初步

void main()
{
    int ival = 42;
    int *p = &ival;
    cout << "p: "<< p<<"\n"
         << "*p: "<<*p;
}

// p:0015FE28    访问变量ival的地址，或者说p是指向变量ival的指针
// *p:42  *为解引用符，访问ival的对象

void main()
{
    int ival = 42;
    int *p = &ival;
    *p = 0;
    cout << "p: " << p << "\n" 
          << "*p: " << *p<<"\n"
          <<"ival: "<<ival;
}

// p:0028FEE0    访问变量ival的地址，或者说p是指向变量ival的指针
// *p:0  *为解引用符，访问ival的对象
// ival:0


void main()
{
    int ival = 42;
    int &r = ival;  //&紧随类名出现，因此是申明的一部分，r是一个引用
    int *p; //*紧随类型名出现，因此是申明的一部分，p是一个指针
    p = &ival;  //&出现在表达式中，是一个取地址符
    *p = ival;  // *出现在表达式中，是一个解引用符
        int &r2 = *p; //&是申明的一部分，*是一个解引用符
    cout << "p: " << p << "\n" 
        << "*p: " << *p << "\n" 
        << "ival: " << ival <<"\n" 
        << "&ival: " << &ival << "\n"
        << "&r: " << &r << "\n"
        << "&r2: " << &r2;
}

p: 002AFE88
*p: 42
ival: 42
&ival: 002AFE88
&r: 002AFE88
&r2: 002AFE88



void main()
{
    int ival = 42;
    int r = ival;
    int *p = &ival;
    cout << "p: " << p << "\n" 
        << "*p: " << *p << "\n" 
        << "ival: " << ival <<"\n" 
        << "&ival: " << &ival << "\n"
        << "&r: " << &r << "\n"
        << "r: " << r;
}

// 不知道在定义的时候加&或者*和定义完成后重新赋值的时候加&或者*有什么区别呢？

下面是引用和指针的问题：

void main()
{
    int ival = 42;
    int &t = ival;  // t为引用，在修改了t=0之后，p也进行了修改
    int *p;
    p = &t;
    cout << "p: " << p << "\n" << "*p: " << *p << endl;
    cout << "ival: " << ival << "\n" << "&ival: " << &ival << endl;
    t = 0;
    //*p = 0;
    cout << "p: " << p << "\n" << "*p: " << *p << endl;
    cout << "ival: " << ival << "\n" << "&ival: " << &ival << endl;
}

/*
p: 0028F93C
*p: 42
ival: 42
&ival: 0028F93C

p: 0028F93C
*p: 0
ival: 0
&ival: 0028F93C
*/



void main()
{
    int ival = 42;
    int *t = &ival;  // t为指针指向ival的地址，在t修改了后，p的指针仍指向ival的地址
    int *p;
    p = t;
    cout << "p: " << p << "\n" << "*p: " << *p << endl;
    cout << "ival: " << ival << "\n" << "&ival: " << &ival << endl;
    t = 0;
    //*p = 0;
    cout << "p: " << p << "\n" << "*p: " << *p << endl;
    cout << "ival: " << ival << "\n" << "&ival: " << &ival << endl;
}

/*
p: 0037FBAC
*p: 42
ival: 42
&ival: 0037FBAC
p: 0037FBAC
*p: 42
ival: 42
&ival: 0037FBAC
*/