New to pointers - allocation problem

Hi,

I'm trying to use an array of strings as:

char *str[MAX]

I'm trying to store each a_id in the str. But after running the follwoing code I find that only the 1st a_id was assigned in all str indices.I've not assigned str to anything!
I know that its some sort of stale pointer thats creating the problem.How to allocate for str?
Could you please shed some light upon this?

Code:

---


while(!feof(f))
                  {
                        fgets (all_id, 100 , f);
                        sscanf (all_id,"%*s %s %s",a_id,d_id);
                        str[i] = a_id;

---

Thanks,
Angkar

Code:

---

sscanf (all_id,"%*s %s %s",a_id,d_id);

---

Why is there a * there?

Why it's bad to use feof() to control a loop
~Sven

Whats the solution then?

It should probably be

Code:

---

fgets (all_id, 100 , f);
sscanf (all_id,"%s %s %s",a_id,d_id);
str[][i] = a_id;

---

Identifiers dont have an asterisk.

When you have an array of strings like this, the first dimension is the actual "string" and the second one is that string's place in the array. Since you indexed the first dimension like that, you overwrote the first character of each string.

str[][i] = a_id; is not working - a syntax error!
also * was in sscanf - its used to ignore the string that I dont want to read!

I see, well write str*[i] = a_id; istead.

Now if I print within the while loop str is showing all the values!
But when I try to print outside its losing them!
Strange!

Outside the loop, treat it like a normal array.

Code:

---

printf( "%s \n", str[i]);

---

where i is whatever string you need.

You need to dereference str to change it, but not to read.

There is no difference between *[] and [][] i think!
And I'm using printf( "%s \n", str[i]); outside the loop!Somhow its value is changin there!

You need to allocate memory for each row of data

Code:

---

while ( i < MAX && fgets (all_id, 100 , f) != NULL ) {
  if ( sscanf (all_id,"%*s %s %s",a_id,d_id) == 2 ) {
    str[i] = malloc ( strlen(a_id) + 1 );
    strcpy(str[i], a_id);
    i++;
  }
}

---

Assuming that is all your other variables like a_id are arrays and not pointers.