a question about malloc

I write a program with c for digital unix.I use malloc to ask for some space to use and free it later.But the malloc will fault when the program run for a long time.Who can tell me what about the malloc function.Thanks.

This seems to be a problem of non freed resources.
Dont forget to free malloc resources with free functions because of fragmented memory problems.

malloc can be a bit tricky, as the previous reply stated, you MUST free up the space you requested, but you also have to ask for the right amount of space, for example if I want a char * that will hold a 30 character string, the following will fail:
char *my_string;
my_string = (char *) malloc(sizeof(char) * 30);

It will either cause a segmenation violation, a sigbus, or it will work fine. The problem is that you of course need 31 bytes for a string that is 30 long, 30 for the string and one for the null terminator. I've had this problem cause some very hard to track down errors. Hope this helps.

I has free what I had asked for.I use a struct like this:
struct str{
char name[11];
int age;
};

struct str temp;

temp=(struct str*)malloc(sizeof(struct str));

when it run some time,it return null.I think it isn't the situation what you said.Do you?