指针变量也被分配了一个内存地址吗? [英] Is a pointer variable also assigned a memory address?

问题描述

在C ++中，在堆栈上，为一个简单的变量分配了一个内存地址，以便我们可以使用指针来包含该内存以指向它；那么指针还被分配了一个内存地址吗?

In C++, on the stack, a simple variable is assigned a memory address so that we can use a pointer to contain this memory to point to it; then is a pointer also assigned a memory address?

如果是，我们可以有一个指针的指针吗?

If yes, can we have a pointer of pointers?

推荐答案

是的，您是正确的.我们可以使用指向指针的指针:

Yes, you are right. We can have pointers to pointers:

int a;
int b;
int * pa = &a;
int ** ppa = &pa;

// set a to 10
**ppa = 10;

// set pa so it points to b. and then set b to 11.
*ppa = &b;
**ppa = 11;

从右到左读取它: ppa是一个指向int的指针.不限于**.您可以根据需要设置任意多个级别. int ***将是指向int 的指针的指针.

Read it from right to left: ppa is a pointer to a pointer to an int . It's not limited to ** . You can have as many levels as you want. int *** would be a pointer to pointer to pointer to int .

我回答了一个类似的问题，关于原始变量是否在这里有地址: 是否为基元分配了内存地址?，指针也是如此.简而言之，如果您从不获取对象的地址，则编译器不必为它分配地址:它可以将其值保存在寄存器中.

I answered a similar question regarding whether primitive variables have addresses here: Is primitive assigned a memory address?, the same applies to pointers too. In short, if you never take the address of an object, the compiler doesn't have to assign it an address: It can keep its value in a register.

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