pointer to array of structure

Hello, I am not sure why I am not able to print member structure member aa. Can someone please help? Code and output below:

Code:

#include <ansi_c.h>
// Structuer passing example

typedef struct
{
    char t[10];
    int w, h, a;
    char *aa;
} area; // area is declared to be of type struct


void assign(void); // prototypes 
area table[20]; // declare an array of 20 area's
area (*p)[20] = &table; // declare and define pointer-to-array of 20 area's

void assign()  // use it
{
    char str[10],str2[10];
    
    for(int i=0; i<20; i++)
    {
        sprintf(str,"T%d\0",i);
        strcpy((*p)[i].t,str);
        (*p)[i].w = i; // dereference p to get to table, 
                            // [i] to access i-th structure and 
                            // .w to get the w member of it 
        (*p)[i].h = i;
        (*p)[i].a = (*p)[i].w*(*p)[i].h;
        sprintf(str2,"A%d\0",i);
        (*p)[i].aa = str2;
        printf("aa[%d]=%s\n",i,(*p)[i].aa);
    }
}

int main(void)
{
    assign();   // initial table
    
    if(&p != NULL)
    {                                        
        printf("No.  TT W * H = Area  AA\n========================\n");
        for(int j=0; j<20; j++)
        {
            printf("[%2d] %-3s %2d %2d   %3d %3s\n",j, (*p)[j].t,(*p)[j].w,(*p)[j].h,(*p)[j].a,(*p)[j].aa);  // why doest this work aa (prints garbage)?
        }
    }
    else
        printf("pTable (= NULL) not pointing to anything (i.e. has not been intiaialized\n");
            
    getchar();
    
    return 0;
}

result printed:
aa[0]=A0
aa[1]=A1
aa[2]=A2
aa[3]=A3
aa[4]=A4
aa[5]=A5
aa[6]=A6
aa[7]=A7
aa[8]=A8
aa[9]=A9
aa[10]=A10
aa[11]=A11
aa[12]=A12
aa[13]=A13
aa[14]=A14
aa[15]=A15
aa[16]=A16
aa[17]=A17
aa[18]=A18
aa[19]=A19
No. TT W * H = Area AA
========================
[ 0] T0 0 0 0 H?ÎhO
XhH?Îh?
[ 1] T1 1 1 1 H?ÎhO
XhH?Îh?
[ 2] T2 2 2 4 H?ÎhO
XhH?Îh?
[ 3] T3 3 3 9 H?ÎhO
XhH?Îh?
[ 4] T4 4 4 16 H?ÎhO
XhH?Îh?
[ 5] T5 5 5 25 H?ÎhO
XhH?Îh?
[ 6] T6 6 6 36 H?ÎhO
XhH?Îh?
[ 7] T7 7 7 49 H?ÎhO
XhH?Îh?
[ 8] T8 8 8 64 H?ÎhO
XhH?Îh?
[ 9] T9 9 9 81 H?ÎhO
XhH?Îh?
[10] T10 10 10 100 H?ÎhO
XhH?Îh?
[11] T11 11 11 121 H?ÎhO
XhH?Îh?
[12] T12 12 12 144 H?ÎhO
XhH?Îh?
[13] T13 13 13 169 H?ÎhO
XhH?Îh?
[14] T14 14 14 196 H?ÎhO
XhH?Îh?
[15] T15 15 15 225 H?ÎhO
XhH?Îh?
[16] T16 16 16 256 H?ÎhO
XhH?Îh?
[17] T17 17 17 289 H?ÎhO
XhH?Îh?
[18] T18 18 18 324 H?ÎhO
XhH?Îh?
[19] T19 19 19 361 H?ÎhO
XhH?Îh?

> (*p)[i].aa = str2;
Because this does NOT make a copy of the string.
All you end up with is 20 pointers, all pointing at str2 - well until the function ends, at which point str2 goes out of scope and you have 20 pointers all pointing at garbage.

The simple fix, until you know what you're doing is

Code:

typedef struct
{
    char t[10];
    int w, h, a;
    char aa[20];
} area; // area is declared to be of type struct

followed by

Code:

strcpy((*p)[i].aa,str2);

Salem, thx for your response.
So are you saying I cannot use a char pointer as a member inside a structure (i.e. it would have to be a string...like char name[10] instead of char* name)?

You can use a char pointer, but you need to call malloc() to allocate the right amount of space for the string (then copy it), and then later on make sure you call free() when you're done.

Once you start managing memory yourself, it's a significant step up in the difficulty in writing code.