C：内存分配-以下结构是否是幼稚的解决方法？

Question

I'm currently rolling my own split, trim and other utility string functions in C. While rummaging about SO I've ascertained that functions like strdup() are, in general, considered evil because it allocates memory (unlike other string functions from the same library).

However, it seems inevitable that my functions can be written in such a way that they do not allocate memory. I'm trying to resolve this as best as I can. Currently, I've left all input strings alone (const), and returned a pointer to a new string and documenting that the return must later be free'd.

I'm pondering if there is a better way, and this idea struck me. I'm trying to figure out if it's actually a good idea or if it's a naive one. And therein lies my question, is the following solution adviseable? If not, how come?

My idea is this, I'll create a struct like so:

typedef struct string {
    char *str;
    bool initialized;
} string;

using it for all my string manipulation work. At the end of all related functions, just before the return statement I'll call another function, let's call it destroy , on the input string (which wouldn't be a char pointer but the aforementioned struct). That function in turn would check the boolean, ìnitialized , which denotes that memory has been allocated and if so subsequently free it.

Answer 1

typedef struct string {
    char *str;
    bool initialized;
} string;

That function in turn would check the boolean, ìnitialized , which denotes that memory has been allocated and if so subsequently free it.

You do not need a struct to do that. Initialize with a null pointer any char* pointer that you could have wanted to use your struct for, and you can pass it to free() or realloc() without having to wonder whether or not it has been further assigned.