Make Realloc behave like Calloc - dynamic

Question

How can I force Realloc to behave like calloc?
For instance:
I have the following structs:
typedef struct bucket0{
int hashID;
Registry registry;
}Bucket;
typedef struct table0{
int tSize;
int tElements;
Bucket** content;
}Table;
and I have the following code in order to grow the table:
int grow(Table* table){
Bucket** tempPtr;
//grow will add 1 to the number available buckets, and double it.
table->tSize++; //add 1
table->tSize *= 2; //double element
if(!table->content){
//table will be generated for the first time
table->content = (Bucket**)(calloc(sizeof(Bucket*), table->tSize));
} else {
//realloc content
tempPtr = (Bucket**)realloc(table->content, sizeof(Bucket)*table->tSize);
if(tempPtr){
table->content = tempPtr;
return 0;
}else{
return 1000;//table could not grow
}
}
}
When I execute it, the table grows properly, and MOST of the "Buckets" in it are initialized as a NULL ptr. However, not all of them are.
How can I make Realloc behave like calloc? in the sense that when it creates new "buckets" they initialize to NULL

Answer 1

Strictly speaking, you shouldn't be relying on calloc (or memset, for that matter) to set pointers to null. C doesn't guarantee that null pointers are represented by all-zero bytes in memory.
Quoting from the comp.lang.C FAQ question 7.31:
Don't rely on calloc's zero fill too much (see below); usually, it's best to initialize data structures yourself, on a field-by-field basis, especially if there are pointer fields.
calloc's zero fill is all-bits-zero, and is therefore guaranteed to yield the value 0 for all integral types (including '\0' for character types). But it does not guarantee useful null pointer values (see section 5 of this list) or floating-point zero values.
It's safer to initialize the individual structure fields yourself. You can create a static const one as a template, with its content initialized to NULL, and then memcpy it to each element of your dynamically-allocated array.