第08天C语言(13):多级指针

一、概念

/*
 char c = 'a';
 char *cp;
 cp = &c;
 char **cpp;
 cpp = &cp;
 
 *cp == c
 *cpp == cp;
 **cpp == *(*cp) == *cp == c
 */

二、代码

#include <stdio.h>
int main()
{
    /*
    char charValue = 'l';
    char *p;
    p = &charValue;
//    charValue = 'n';
    *p = 'n';
    printf("%c\n",*p);
     */
    
    /*
    char charValue = 'l';
    // 1.拷贝需要指向的变量的 数据类型 和名称
    // 2.在数据类型 和变量名称 之间加上一颗星
    // 3.修改变量名称
    char *charValueP;
    
    charValueP = &charValue;

    // 1.拷贝需要指向的变量的 数据类型 和名称
    // 2.在数据类型 和变量名称 之间加上一颗星
    // 3.修改变量名称
    char **charValuePP; // 不管有几颗* 只要是指针 就占用8个字节
    printf("size = %lu\n",sizeof(charValuePP));
    charValuePP = &charValueP;

//    charValue = 'j';
    // *charValueP == charValue
//    *charValueP = 'j';
//    *charValuePP == charValuePP
//    printf("%c\n",*charValueP);
    
    // &charValue == charValueP
    printf("&charValue = %p\n",&charValue);
    printf("charValueP = %p\n",charValueP);
    
    // &charValueP == charValuePP
    printf("&charValueP = %p\n",&charValueP);
    printf("charValuePP = %p\n",charValuePP);
    
    // *charValuePP == charValueP
    // *pp = p
    // **charValuePP = *(*charValueP) = *charValueP = l
    **charValuePP = 'n';
    printf("%c\n",charValue);
    printf("%c\n",**charValuePP);
     */
    
    
    char c = 'a';
    char *cp;
    cp = &c;
    char **cpp;
    cpp = &cp;
    char ***cppp;
    cppp = &cpp;
    printf("cppp = %c\n",***cppp);

    /*
     *cp == c
     *cpp == cp;
     **cpp == *(*cp) == *cp == c
     
     多级指针的操作,最简单的方式,就是通过几颗星来存储,就通过几个星来访问
     
     还有一种方式 就是画图,看图片中有几个箭头,就用几颗星来访问
     */
    
    printf("c = %c\n",c);
    printf("*cp = %c\n",*cp);
    
    printf("&c = %p\n",&c);
    printf("cp = %p\n",cp);
    printf("*cpp = %p\n",*cpp);
    
    printf("**cpp = %c\n",**cpp);

    
    return 0;
}