声明要作为参数传递的临时结构-结构被覆盖。 如何在新的内存位置声明该结构？

Question

I am trying to initialize a new struct during each iteration of this loop to pass into a function; the problem is that the same struct keeps being written over or reused (the memory address is the same). How do I declare a new structure that won't be overwritten so that I can pass the pointer to another function?

while(dirs[i] != NULL){
    thread_arg narg;

Answer 1

If you want the data to have persistence beyond that iteration of your while loop whilst other iterations continue then you need to dynamically allocate, like this:

while(dirs[i] != NULL){
    thread_arg * nargp = (thread_arg *) malloc(sizeof(thread_arg)); 

You have a pointer now instead of a value, but that's probably appropriate to your use (ie, you should be thinking of it as a pointer rather than a value probably).

You need to free the data when you have finished with it of course. Where/how you do that depends on your use case - you mention you are passing the data to another function, so if that function uses it and there's no other use, then one solution is that function could free it ( free(nargp) ) before returning.