用两种方式再述指针以及指针的指针

这篇文档记录用更简短更清晰的示例来理解指针。

#include <stdio.h>

int main() {
    int a = 50; //定义普通变量a
    int* aPtr = &a; //定义指针变量aPtr,下面统一称之为变量,
    int** bPtr = &aPtr; //定义指向指针变量的指针变量bPtr,下面统一称之为变量
    //方式一:用打印地址和地址值的方式作推导，来理解指针以及指针的指针的概念
    printf("variable a value = %d\n",a); //打印变量a的值
    printf("variable a address = %p\n",&a);//打印变量a的地址
    printf("\n");
    printf("variable aPtr value = %p\n",aPtr);//打印变量aPtr的值
    printf("variable aPtr address = %p\n",&aPtr);//打印变量aPtr的地址
    printf("variable aPtr -> value = %d\n",*aPtr);//把变量aPtr的值作为地址，打印地址上存储的值,即a的值
    printf("\n");
    printf("variable bPtr value = %p\n",bPtr);//打印变量bPtr的值
    printf("variable bPtr address = %p\n",&bPtr);//打印变量bPtr的地址
    printf("variable bPtr -> value = %p\n",*bPtr);//把变量bPtr的值作为地址，打印地址上存储的值，即*&aPtr = aPtr = &a的的值
    printf("\n");
    printf("variable bPtr -> value = %d\n",**bPtr);//把*bPtr作为地址，打印地址上存储的值，即*(*&aPtr) = *(aPtr) = *(&a) = a的值
    //方式二:用变量共性作推导，来理解指针以及指针的指针的概念
    //int a = 50; //定义普通变量a,a = 50
    //int* aPtr = &a; //定义指针变量aPtr,下面统一称之为变量,参照变量a = 50,aPtr = &a,*aPtr = *(&a) = a
    //int** bPtr = &aPtr; //定义指向指针变量的指针变量bPtr,下面统一称之为变量,
                          //参照变量a = 50,bPtr = &aPtr,*bPtr = *(&aPtr) = aPtr = &a,**bPtr = *(&a) = a
}

variable a value = 50
variable a address = 0x7ffee5660b5c

variable aPtr value = 0x7ffee5660b5c
variable aPtr address = 0x7ffee5660b50
variable aPtr -> value = 50

variable bPtr value = 0x7ffee5660b50
variable bPtr address = 0x7ffee5660b48
variable bPtr -> value = 0x7ffee5660b5c

variable bPtr -> value = 50