Allocate space for struct pointer in subfunction

Question

How can I allocate memory for a struct pointer and assign value to it\'s member in a subfunction?

The following code will compile but not execute:

#i         


        

Answer 1

you must change your code like that:

    #include 
    #include 
    #include 

    struct _struct {char *str;};
    void allocate_and_initialize(struct _struct **s)
    {
        *s = (_struct*)calloc(sizeof(struct _struct), 1);
        (*s)->str = (char*)calloc(sizeof(char), 12);
        strcpy((*s)->str, "hello world");
    }
    int main(void)
    {
        struct _struct *s;
        allocate_and_initialize(&s);
        printf("%s\n", s->str);

        return 0;
    }

The reason is, that you change the adress of the pointer, but not the "content" of the pointer. So, if you code in c, you have to use a "double" pointer. If you code in c++ you can use a reference.