Initialize all variables when they are declared in your software. Even if it is a trivial scalar variable, go ahead and initialize it. Integers and floats can typically be initialized to -1 or 0, while pointers can be initialized to NULL. This simple habit can help uncover many problems that occur when the validity of a value is not checked before it is used. There is no guarantee what the value of a variable will be when it is created. Picking a known initial value to start out with can prevent garbage data from being interpreted as valid information.
A similar argument applies to memory regions that are dynamically allocated. Any dynamically allocated structure or variable should at least be zeroed out before being used in the code. This can be done with the memset() function:
foopointer = (struct foostruct)malloc(sizeof(struct foostruct));
if(foopointer == NULL)
{
/* alloc failed */
return(some error value);
}
memset(foopointer, 0, sizeof(struct foostruct));
If there are sentinal values other than 0 for elements contained in your struct, they should be set as well.