Help with Structure and pointers compare

[lisedaton]

hi all!!!!

im trying to do strcmp to a char in a structure and and char* and im getting a msg error: dereferencing pointer to incomplete type....

can somebody explain me what is that and give me an idea how to resolve it?

thanx in advanced!

[Dave Sinkula]

If you want help with code, it's generally a good idea to post code. Otherwise, I trust what the compiler has told you is correct and as clear as possible.

[lisedaton]

if i have something like this.... and im getting an error msg on strcpy: " dereferencing pointer to complete type" , what is wrong?

im getting the same msg for most of my pointers and i dont know why, so i decided to try something like this simpler but i still dont see it.... can you help me:::

#include <stdio.h>
#include <malloc.h>
#include <string.h>

struct strs
{
       char x;
};
typedef struct str strs;

int main()
{
strs *hola;
hola= (strs*)malloc(sizeof(strs*)*3);
char names[3][5] = {"DANA",
"RANI","SHIR"};
char *pnames[3];
int i;
for(i=0; i<3; i++)
{
pnames[i] = names[i];
strcpy(hola->x, pnames[i]);
}
system ("pause");
return (0);
}

[Dave Sinkula]

Typo for starters:

typedef struct strs strs;

Structure element x is a single char: there is no room for it to be a string. So using strcpy to compare what isn't a string is not going to be right.

[edit]If I were to try to rename some variables to make more sense to me and make a few other changes, I might rewrite your code like this:

#include <stdio.h>
#include <stdlib.h> /* not <malloc.h> */
#include <string.h>

/** The number of strings and their maximum size. */
#define COUNT  3
#define SIZE   5

struct type
{
   char text[SIZE];
};

int main(void)
{
   const char names[COUNT][SIZE] = { "DANA", "RANI", "SHIR" };
   struct type *array = malloc(COUNT * sizeof *array);
   if ( array )
   {
      int i;
      for ( i = 0; i < COUNT; ++i )
      {
         strcpy(array[i].text, names[i]);
      }

      /* Print array elements or do something else with it? */

      free(array);
   }
// system ("pause");
   return 0;
}

[Narue]

I suspect you're compiling your C code as C++. That's not recommended unless you really know what you're doing. Anyway:

>#include <malloc.h>
<malloc.h> is archaic and non-standard. Use <stdlib.h> instead.

/* Wrong */
struct strs
{
       char x;
};
typedef struct str strs;

Notice that your typedef is using a structure that was never defined? I don't see a struct str anywhere in your code, but there is a struct strs. You can use the same name for the structure and the typedef because they're in different name spaces[1]:

/* Yay! */
struct strs
{
       char x;
};
typedef struct strs strs;

>strcpy(hola->x, pnames); hola->x is a char, not a pointer to char. It's not a compatible type for use with strcpy.

>system ("pause");
You want to include <stdlib.h> for this function.

[1] Once again I'm risking confusion with C++ namespaces by introducing a space in the name. :D