Question

Please have a look at the following code and tell me where does ***ptr locates ? i.e. i have a feelings that ***ptr actually locates at ptr[0][0][0] Am I wrong ? The following is a 3d representation of pointer. where I am trying to assign some characters and later i wanted to test what is the index of ***ptr? will be waiting

#include<stdio.h>
#include<conio.h>
#define row 5
#define rw 3
#define col 10


char ***ptr;
int i,j,k;


void main()
{

clrscr();

ptr=(char *)malloc(row*sizeof(char *));

for(i=0;i<row;i++)
    {
        *(ptr+row)=(char *)malloc(rw*sizeof(char *));
        printf("	:
");

           for(j=0;j<rw;j++)
           {
           *(*(ptr+row)+rw)=(char *)malloc(col*sizeof(char *));
           if(i==0 && j==0)
               {       //   *(*(ptr+row)+rw)="kabul";
            **ptr="zzz";

               }
           else
            *(*(ptr+row)+rw)="abul";
           printf("	address=%d %d%d = %s
",((ptr+row)+rw),i,j,*(*(ptr+row)+rw));

           }

         printf("
");
    }


printf("%c %d",***ptr,ptr);
getch();
}

Answer 1

首先,我觉得你的表象很难读。

回答您的问题,是:ptr[0][0][0] 是***ptr的同义词。由于<代码>a[b]按定义等于*(a+b),因此<代码>ptr[0]等于<代码>_ptr等。

页: 1

#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#define row 5
#define rw 3
#define col 10


char ***ptr;

int main()
{
    int i, j;

    ptr = (char***)malloc(row * sizeof(char **));

    for(i = 0; i < row; i++)
    {
        ptr[i]= (char**)malloc(rw * sizeof(char *));
        printf("	:
");

        for(j = 0; j < rw; j++)
        {
            ptr[i][j] = (char*)malloc(col * sizeof(char));
            if (i == 0 && j == 0)
            {
                strcpy(ptr[i][j], "zzz");
            }
            else
            {
                strcpy(ptr[i][j], "abul");
            }
            printf("	address=%p %d,%d = %s
", ptr[i][j], i, j, ptr[i][j]);

        }
        printf("
");
    }
    return;
}

注:

Never write void main in C or C++. And throw away any book that prints it.
The argument of malloc is usually the number of elements times the size of the element. Place special attention to the real type that you intend to use.
The return of malloc is usually cast to the type pointer-to-the-type-of-the-element.
The index in the arrays should be i and j, not row and rw.
Why all the *(ptr + x) stuff? That s why we have the ptr[x] syntax.
You probably want to use strcpy to fill your strings, but difficult to say without explaining the problem.
When you want to printf a pointer, use %p.
If you use malloc, include <stdlib.h>.
Prefer local variables (i, j) to global ones, particularly for loops.
And a few other minor changes here and there...

PS:<conio.h>? 真的? 你们是否仍在使用Turbo-C或什么?

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