Thread: malloc and pointers

hi all

Code:

#include <stdio.h>
#include <stdlib.h>

main()
{
      char *aa;
     
       if((aa=malloc(100 *sizeof(char)))==NULL)
          {
                        printf("Alloctaing Error\n");
                        exit(-1);
           }
      
      printf("%d",sizeof(aa));
}

it give me 4 as output !!!!!!!!!!!!!
but

Code:

#include <stdio.h>
#include <stdlib.h>

main()
{
      char  aa[100];
           
      printf("%d",sizeof(aa));
}

gives me 100 !!!
so where is the problem ?
why in the first code when i used malloc it gives me 4 but in the second code give me the object aa size ??
thanks in advance