Question

I have a structure declared and allocated in this way

typedef {
      char* a; char* b; int c; int d; FILE *e;
} t;
[...]

    ready= malloc(sizeof(t));
    strncpy (ready->a, ss1, length);
    strncpy (ready->b, ss2, length);
    ready->c= f; ready->d= g;
    ready->e= fopen(file, "w");

that I want to pass to a thread with

pthread_create(thread_id, NULL, worker_start, &ready);

when I begin to do some stuff in the thread function it’s clear that the fields that I had initialized in the main before calling the create are not defined in the thread.

void* worker_start(void *param) {
    t *current;

    current = (t*) param;
    ...
}

What’s wrong with the code? Am I doing something bad here?

Answer 1

When you’re passing the pointer to the thread, you pass it as a pointer to pointer (due to you using the address-of operator &). You don’t need to do that, and in the thread function you don’t treat it as a pointer-to-pointer but just plain pointer.

Remove the ampersand (&) when creating the thread and things should work much better.